Interventions for preventing excessive weight gain during pregnancy

Benja Muktabhant; Pisake Lumbiganon; Chetta Ngamjarus; Therese Dowswell

doi:10.1002/14651858.CD007145.pub2

. Author manuscript; available in PMC: 2014 Sep 15.

Published in final edited form as: Cochrane Database Syst Rev. 2012 Apr 18;4:CD007145. doi: 10.1002/14651858.CD007145.pub2

Interventions for preventing excessive weight gain during pregnancy

Benja Muktabhant ¹, Pisake Lumbiganon ², Chetta Ngamjarus ³, Therese Dowswell ⁴

PMCID: PMC4163963 EMSID: EMS57971 PMID: 22513947

Abstract

Background

Excessive weight gain during pregnancy is associated with multiple maternal and neonatal complications. However, interventions to prevent excessive weight gain during pregnancy have not been adequately evaluated.

Objectives

To evaluate the effectiveness of interventions for preventing excessive weight gain during pregnancy and associated pregnancy complications.

Search methods

We searched the Cochrane Pregnancy and Childbirth Group’s Trials Register (20 October 2011) and MEDLINE (1966 to 20 October 2011).

Selection criteria

All randomised controlled trials and quasi-randomised trials of interventions for preventing excessive weight gain during pregnancy.

Data collection and analysis

We assessed for inclusion all potential studies we identified as a result of the search strategy. At least two review authors independently assessed trial quality and extracted data. We resolved discrepancies through discussion. We have presented results using risk ratio (RR) for categorical data and mean difference for continuous data. We analysed data using a fixed-effect model.

Main results

We included 28 studies involving 3976 women; 27 of these studies with 3964 women contributed data to the analyses. Interventions focused on a broad range of interventions. However, for most outcomes we could not combine data in a meta-analysis, and where we did pool data, no more than two or three studies could be combined for a particular intervention and outcome. Overall, results from this review were mainly not statistically significant, and where there did appear to be differences between intervention and control groups, results were not consistent. For women in general clinic populations one (behavioural counselling versus standard care) of three interventions examined was associated with a reduction in the rate of excessive weight gain (RR 0.72, 95% confidence interval 0.54 to 0.95); for women in high-risk groups no intervention appeared to reduce excess weight gain. There were inconsistent results for mean weight gain (reported in all but one of the included studies). We found a statistically significant effect on mean weight gain for five interventions in the general population and for two interventions in high-risk groups.

Most studies did not show statistically significant effects on maternal complications, and none reported significant effects on adverse neonatal outcomes.

Authors’ conclusions

There is not enough evidence to recommend any intervention for preventing excessive weight gain during pregnancy, due to the significant methodological limitations of included studies and the small observed effect sizes. More high-quality randomised controlled trials with adequate sample sizes are required to evaluate the effectiveness of potential interventions.

Medical Subject Headings (MeSH): * Weight Gain; Counseling; Diet; Exercise; Infant, Newborn; Overweight [complications; * prevention & control]; Pregnancy Complications [* prevention & control]; Randomized Controlled Trials as Topic

MeSH check words: Female, Humans, Pregnancy

BACKGROUND

Description of the condition

Pregnancy weight gain guidelines

In 2009, the Institute of Medicines (IOM) in the United States updated earlier guidelines on weight gain during pregnancy (Medicine 1990; Medicine 2009). The report set out specific ranges of weight gain for women with different prepregnancy weights: suggesting that underweight women (body mass index (BMI) less than 18.5 kg/m²) gain 28 to 40 lbs (12.5 kg to 18 kg); normal weight women (BMI 18.5 kg/m² to 24.9 kg/m²) gain 25 to 35 lbs (11.5 kg to 16 kg); whereas overweight women (BMI 25 kg/m² to 29.9 kg/m²) were advised to gain between 15 and 25 lbs (7 to 11.5 kg) and obese women (BMI at least 30 kg/m²) to gain between 11 and 20 lbs (5 to 9 kg) (Medicine 2009).

Previous guidelines from the IOM (Medicine 1990) had been widely adopted but not universally accepted. However, a review of relevant information confirmed that pregnancy weight gain within the IOM’s recommended ranges was associated with the best outcomes for both mothers and infants, and that weight gain within the IOM’s recommended ranges is not harmful for the mothers or for their infants (Abrams 2000).

No official recommendations or clinical guidelines for weight gain during pregnancy exist in the United Kingdom (UK) (Ford 2001). However, a recent report from the UK Centre for Maternal and Child Enquiries (CMACE 2010) suggested a more comprehensive guidance for the care of overweight and obese women, and recommended weighing women in the third trimester and again when women are admitted in labour. Guidelines in other countries have also recommended monitoring weight gain in pregnancy. The optimal gestational weight gain in Swedish women was 4 kg to 10 kg for BMI less than 20; 2 kg to 10 kg for BMI 20 to 24.9. For women with a BMI of 25 to 29.9, a weight gain of less than 9 kg was recommended, and pregnant women with a BMI of 30 or more were recommended to gain less than 6 kg in weight (Cedergren 2007). Pregnant Asian women in general had lower weight gains in comparison to pregnant women in Europe and North America (Abrams 1995; Siega-Riz 1993). Hence, maternal weight gain recommendations based on data from high-income countries may not be applicable to Asian women. A study to produce ethnicspecific maternal weight gain recommendations was performed in China. The recommended total weight gain was 13 kg to 16.7 kg, 11 kg to 16.4 kg, and 7.1 kg to 14.4 kg respectively for women of low (BMI less than 19), moderate (BMI 19 to 23.5), and high (BMI greater than 23.5) BMI measurement (Wong 2000).

Trends in pregnancy weight gain

Although the 1990 IOM guidelines have now been promoted for two decades it has been estimated that over this time only 30% to 40% of pregnant women in the United States gain gestational weight within the IOM recommended ranges (Abrams 2000; Cogswell 1999; Medicine 1990; Olson 2003). Furthermore, gestational weight gain above the guidelines is more common than gestational weight gain below (Stotland 2006). Several studies on gestational weight gain in the USA and Europe indicate that about 20% to 40% of women are gaining weight above the recommendations (Cedergren 2006; Medicine 2009; Olson 2003) and the prevalence of excessive gestational weight gain is increasing (Abrams 2000; Rhodes 2003; Schieve 1998). A retrospective cohort study undertaken to examine the trend in weight gain during pregnancy of 1,463,936 women over 16 years in North Carolina found that the proportion of women gaining excessive gestational weight (more than 18 kg) increased from 15.5% in 1988 to 19.5% in 2003; an additional 40 women per 1000 gained excessive weight by 2003 (Helms 2006). The recent IOM report summarised the situation in a number of countries; compared with two decades earlier “Women today are also heavier; a greater percentage of them are entering pregnancy overweight or obese, and many are gaining too much weight during pregnancy” (Medicine 2009).

Weight gain during pregnancy is generally inversely proportional to prepregnancy weight category. Overall, underweight women were least likely to exceed weight gain recommendations although obese women tended to gain less weight than normal and overweight women (Abrams 1989; Bianco 1998; Edwards 1996; Walling 2006). For instance, two large population-based studies, in Sweden and the United States, reported similar findings. They found that approximately 30% of average and overweight women had high gestational weight gain, whereas approximately 20% of obese women had high gestational weight gain (Cedergren 2006; Cogswell 1995).

Pregnancy weight gain and outcomes for mothers and infants

It is well known from large studies in a number of countries that excessive weight gain during pregnancy is associated with multiple maternal and neonatal complications. Retrospective cohort studies have examined the relationship between gestational weight gain and adverse neonatal outcomes among infants born at term. It was established that gestational weight gain above the upper limit of the IOM guideline was associated with a low five-minute Apgar score, seizure, hypoglycaemia, polycythaemia, meconium aspiration syndrome and large-for-gestational age compared with women within weight gain guidelines (Hedderson 2006; Stotland 2006). Obese women with low gestational weight gain had a decreased risk for the following outcomes: pre-eclampsia, caesarean section, instrumental delivery, and large-for-gestational age births, whereas, excessive weight gain of obese women increased the risk for caesarean delivery in all maternal BMI classes (Cedergren 2006).

Findings from a national study in the UK revealed that compared with pregnant women in general, obese pregnant women were at increased risk of having a co-morbidity diagnosed before or during pregnancy (in particular pregnancy-induced hypertension and gestational diabetes), were more at risk of having induction of labour and a caesarean birth, were more likely to have postpartum haemorrhage and their babies were at increased risk of stillbirth, neonatal death, of being large for gestational age and more likely to be admitted for special care (CMACE 2010).

There have been a number of studies which conclude that excessive gestational weight gain increases postpartum weight retention (Gunderson 2000; Keppel 1993; Polley 2002; Rooney 2002; Rossner 1997; Scholl 1995) and is related to a two- to three-fold increase in the risk of becoming overweight after delivery (Gunderson 2000). Moreover, mothers who gained more weight during pregnancy had children at higher risk of being overweight in early childhood (Oken 2007).

However, to be too strict in weight gain restriction might not have the expected result. It was established that in three trials involving 384 women, energy or protein restriction of pregnant women who were overweight or exhibited high weight gain significantly reduced weekly maternal weight gain and reduced mean birth-weight but had no effect on pregnancy-induced hypertension or pre-eclampsia. It concluded that protein or energy restriction of pregnant women is unlikely to be beneficial and may be harmful to the infant (Kramer 2003).

Description of the intervention

Dietary control, exercise and eating behaviour modification are the main elements for controlling weight. Pregnancy may be an optimal time to inform and challenge women to change their eating habits and physical activities, and thereby prevent excessive weight gain.

How the intervention might work

There are systematic reviews which aimed to assess the effect of dietary advice, exercise intervention and psychosocial intervention for achieving weight loss in overweight and obese adults. The results of Cochrane review on exercise for overweight or obesity support the use of exercise as a weight loss intervention, particularly when combined with dietary change (Shaw 2006). People who are overweight or obese may benefit from psychological interventions, particularly behavioural and cognitive-behavioural strategies, to enhance weight reduction. The evidence suggests that these measures are predominantly useful when combined with dietary and exercise strategies (Shaw 2005). In addition, overall, weight loss strategies using dietary, physical activity, or behavioural interventions produced significant improvement in weight among people with prediabetes (Norris 2005).

Why it is important to do this review

Given the increasing prevalence and negative consequences of excessive gestational weight gain, preventing excessive weight gain during pregnancy is potentially important. Intervention might help pregnant women to achieve the recommended weight gain, with the objective of ensuring the best possible outcome for their infants and themselves. Although there are Cochrane reviews evaluating the effect of dietary advices, exercise, and psychological interventions on controlling weight, there are no systematic review evaluating interventions for controlling excessive weight gain during pregnancy.

The aim of this review is to identify and systematically review all randomised controlled trials of interventions for limiting weight gain during pregnancy to provide the best available evidence for clinical decision-making and to stimulate further research about preventing excessive weight gain during pregnancy.

OBJECTIVES

To evaluate the effectiveness of interventions for preventing excessive weight gain during pregnancy and associated pregnancy complications.

METHODS

Criteria for considering studies for this review

Types of studies

We have included all randomised controlled trials (RCTs) and quasi-RCTs of interventions aimed at preventing excessive weight gain during pregnancy, irrespective of their country of origin or language.

Types of participants

Pregnant women.

Types of interventions

Any intervention (e.g. nutrition intervention, exercise intervention, health education or counselling) for preventing excessive weight gain compared with routine care or other interventions for preventing excessive weight gain in pregnancy.

Types of outcome measures

Primary outcomes

Excessive weight gain as defined by trialists.

Secondary outcomes

For the mothers

Weight gain.
Low weight gain as defined by trialists.
Preterm birth.
Preterm prelabour rupture of membranes.
Pre-eclampsia or eclampsia.
Need for and indication for induction of labour.
Caesarean delivery.
Postpartum complication including postpartum haemorrhage, wound infection, endometritis, need for antibiotics, perineal trauma, thromboembolic disease, maternal death.
Behaviour modification outcomes: diet, physical activity.

For the newborns

Birthweight greater than 4000 gm or greater than the 90th centile for gestational age and infant sex.
Birthweight less than 2500 gm or less than the 10th centile for gestational age and infant sex.
Complication related to macrosomia including hypoglycaemia, hyperbilirubinaemia, infant birth trauma (palsy, fracture, shoulder dystocia).

Long-term health outcomes

Maternal weight retention postpartum.
Childhood weight.

Search methods for identification of studies

Electronic searches

We contacted the Trials Search Co-ordinator to search the Cochrane Pregnancy and Childbirth Group’s Trials Register (20 October 2011).

The Cochrane Pregnancy and Childbirth Group’s Trials Register is maintained by the Trials Search Co-ordinator and contains trials identified from:

quarterly searches of the Cochrane Central Register of Controlled Trials (CENTRAL);
weekly searches of MEDLINE;
weekly searches of EMBASE;
handsearches of 30 journals and the proceedings of major conferences;
weekly current awareness alerts for a further 44 journals plus monthly BioMed Central email alerts.

Details of the search strategies for CENTRAL and MEDLINE, the list of handsearched journals and conference proceedings, and the list of journals reviewed via the current awareness service can be found in the ‘Specialized Register’ section within the editorial information about the Cochrane Pregnancy and Childbirth Group.

Trials identified through the searching activities described above are given a code (or codes) depending on the topic. The codes are linked to review topics. The Trials Search Co-ordinator searches the register for each review using these codes rather than keywords. In addition, we searched MEDLINE (1966 to 20 October 2011) using the search strategy given in Appendix 1

We did not apply any language restrictions.

Data collection and analysis

Selection of studies

Two review authors independently assessed for inclusion all the potential studies we identified as a result of the search strategy. We resolved any disagreement through discussion and where necessary, by involving a third author.

Data extraction and management

We designed a form to extract data. For eligible studies, two review authors extracted data using the agreed form. We resolved discrepancies through discussion and where necessary, by involving a third author. We entered data into Review Manager software (RevMan 2011) and checked for accuracy.

When information regarding any of the above was unclear, we attempted to contact authors of the original studies to provide further details.

Assessment of risk of bias in included studies

Two review authors independently assessed risk of bias for each study in six domains (sequence generation, allocation concealment, blinding, incomplete outcome data, selective reporting bias, and other sources of bias) using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). We resolved any disagreement by discussion or by involving a third author.

Measures of treatment effect

For dichotomous data, we presented results as summary risk ratio with 95% confidence intervals.

For continuous data, we used the mean difference if outcomes were measured in the same way between trials. We planned to use the standardised mean difference to combine trials that measured the same outcome, but used different methods.

Unit of analysis issues

We included a cluster-randomised trial in the analyses (Luoto 2011) along with individually-randomised trials. We adjusted their sample sizes and event rates using an intraclass correlation coefficient (ICC) of 0.12 estimated by the trial authors and published in Luoto 2010.

Dealing with missing data

The missing standard deviations were imputed from 95% confidence intervals or standard errors. We have reported the results of some included studies in the additional tables when the missing data could not be imputed.

Assessment of heterogeneity

Where we pooled studies in meta-analysis, we assessed statistical heterogeneity in each meta-analysis using the I² statistic. We regarded heterogeneity as substantial if I² was greater than 50% (Higgins 2011).

Assessment of reporting biases

We did not generate funnel plots to assess possible publication bias for the primary outcome because there were not enough studies in each comparison (fewer than 10 studies).

Data synthesis

We carried out statistical analysis using the Review Manager software (RevMan 2011). We used a fixed-effect model to pool studies to produce summary statistics when the I² was less than 50%. On the other hand, when I² was greater than 50%, we repeated the analysis using a random-effects model. We have indicated in the results text when we have used a random-effects model as the pooled result represents an average treatment effect and, in the presence of high heterogeneity, such results should be interpreted with caution.

However, in this version of the review, for most outcomes we could not combine data in a meta-analysis, and where we did pool data,no more than two studies could be combined for a particular intervention and outcome.

Subgroup analysis and investigation of heterogeneity

For our primary outcome we had planned to carry out subgroup analysis by:

prepregnancy BMI: (1) underweight (2) normal weight (3) overweight (4) obese (as defined by trialists);
gestational age at first visit prenatal clinic: (1) 20 weeks or less; or (2) more than 20 weeks;
gestational age at first visit prenatal clinic: (1) 28 weeks or less; or (2) more than 28 weeks.

Gestational age at 28 weeks (early in the third trimester) is the stage at which weight gain is rapidly increasing.

After examining the interventions offered to different population subgroups, we decided that rather than carrying out subgroup analysis by prepregnancy BMI we would present results for women drawn from the general population (and including all weight categories) and high-risk groups (including women with, or at high risk of, gestational diabetes and/or who were overweight or obese at recruitment) in separate comparisons. We made this decision as the clinical management of women in high-risk groups is likely to be different, and the interventions offered to these women were designed specifically to address their high-risk status.

For other subgroup analysis, in this version of the review, we did not carry out planned subgroup analyses, due to insufficient studies contributing data for the primary outcome (a maximum of three studies provided data for our primary outcome in each comparison). We included one cluster trial but again, there were not enough studies to carry out subgroup analysis by studies using different units of randomisation. In future updates if more data become available for existing comparisons, we will carry out planned analysis for the review’s primary outcomes and, where appropriate, we will carry out the subgroup interaction tests available in RevMan 2011.

Sensitivity analysis

We did not carry out sensitivity analysis because only two included studies were combined for the primary outcome.

RESULTS

Description of studies

See: Characteristics of included studies; Characteristics of excluded studies; Characteristics of studies awaiting classification; Characteristics of ongoing studies.

See Characteristics of included studies; Characteristics of excluded studies; Characteristics of studies awaiting classification; Characteristics of ongoing studies.

Results of the search

The search strategies described above identified 63 potential studies. Following application of eligibility criteria, we included 28 studies in this review. We excluded 12 studies. Two studies are currently awaiting assessment (we have contacted authors for more information) and the other 21 studies are ongoing.

Included studies

From 28 included studies, two studies were quasi-RCTs (Bechtel-Blackwell 2002; Moses 2006); one study was a cluster-RCT (Luoto 2011); the remaining studies were RCTs.

Participants: the 28 included studies involved 3976 participants, although one of these studies (with 12 women) did not report on any of the review’s outcomes and has not contributed data to the review (Magee 1990) (we have included information about this trial in the Characteristics of included studies tables, but it is not otherwise discussed in the remaining sections below). Therefore, our findings are based on 27 studies with 3964 participants. The number of participants in each study varied from 20 to more than 300. The age of participants ranged from 25 to 49 years, except for one study (Bechtel-Blackwell 2002) which included adolescent women aged 13 to 18 years.

Settings: two trials (Santos 2005; Vitolo 2011) were conducted in Brazil. One trial (Huang 2011) was conducted in Taiwan. All others were conducted in developed countries: Australia, Belgium, Canada, Denmark, Finland, Spain and the United States of America; however, two of these studies (Hui 2006; Polley 2002) recruited women with low, or low-middle incomes.

Interventions: most of the interventions considered in this review focused on modifying diet and increasing exercise, however, there was considerable variation in the interventions and in the care received by control groups. Interventions included dietary counselling, dietary intervention (e.g. provision of dietary supplements or foodstuffs), exercise counselling, exercise interventions (e.g. supervised exercise sessions), nutritional monitoring, regular weight measurement, computer-assisted self-interview, and the use of an appetite suppressant drug. These interventions varied in intensity and may have involved more than one approach. Interventions were compared with standard care (which again varied considerably in different settings and was not always well-described) or with another type of intervention. Some studies included more than two arms and these studies may be included in more than one comparison.

Outcomes: only five of the 27 included studies contributing data reported excessive weight gain during pregnancy as a primary outcome. Other studies reported other outcomes, but in all studies except the trial by Callaway 2010, weight gain was reported as one of the outcomes. Some studies reported low weight gain as a outcome. Other outcomes reported included maternal complications and adverse neonatal outcomes.

Only one study (Thornton 2009) reported on postpartum complication outcomes such as postpartum haemorrhage, wound infection, endometritis, need for antibiotics, perineal trauma, thromboembolic disease, or maternal death.

We have reported results separately for pregnant women drawn from the general population (and which may include overweight and obese women) and for known high-risk groups. Of the 27 studies contributing data, 13 specifically recruited women from high-risk groups (i.e. women who were all overweight or obese at recruitment, or women at high risk of gestational diabetes due to weight or other risk factors). Ten studies recruited women from the general pregnant population and results for high- and low-risk women were not reported separately. In four studies (Jeffries 2009; Phelan 2011; Polley 2002; Vitolo 2011), women in all weight categories were recruited, but findings were reported separately for women with low/normal versus overweight/obese prepregnancy weights; therefore, relevant findings from these four studies are reported in both comparisons.

Studies recruiting women in high-risk groups: there were differences in the prepregnancy weight of women recruited to studies; only women who were overweight or obese were recruited in studies by Callaway 2010; Guelinckx 2010; Quinlivan 2011; Rhodes 2010; Santos 2005; Thornton 2009; Wolff 2008; women who were either considered overweight or appeared to be gaining excessive weight in early pregnancy were recruited by Boileau 1968 and Silverman 1971. Women with or at high risk of gestational diabetes were included in four studies (Korpi-Hyovalti 2011; Luoto 2011; Moses 2009; Rae 2000) A mix of underweight, normal, overweight, and obese women were included in studies by Jeffries 2009; Phelan 2011; Polley 2002; Vitolo 2011 with separate results provided for women in the overweight/obese groups.

Interventions in these studies included:

diethylpropion hydrochloride (appetite suppressant drug) versus placebo (Boileau 1968; Silverman 1971);
diet and/or exercise counselling and/or behavioural counselling or weight monitoring versus standard care or routine care (Callaway 2010; Guelinckx 2010; Korpi-Hyovalti 2011; Jeffries 2009; Luoto 2011; Phelan 2011; Polley 2002; Quinlivan 2011; Vitolo 2011; Wolff 2008);
alternative interventions compared (brochure plus counselling versus brochure alone (Guelinckx 2010); high versus low glycaemic diet (Moses 2009); energy restricted diabetic diet versus non-energy restricted diabetic diet (Rae 2000); low glycaemic load versus low fat diet (Rhodes 2010); aerobic exercise plus relaxation versus relaxation alone (Santos 2005); nutritional counselling and weight monitoring versus nutritional counselling alone (Thornton 2009)).

Studies recruiting women in all weight categories: 10 studies included women in all weight categories (Asbee 2009; Barakat 2011; Bechtel-Blackwell 2002; Clapp 2002; Clapp 2002a; Huang 2011; Hui 2006; Jackson 2011; Laitinen 2009; Moses 2006) and as we have mentioned above, four studies reported findings for under and normal weight women separately (Jeffries 2009; Phelan 2011; Polley 2002; Vitolo 2011).

Interventions in these studies varied considerably and the comparison conditions also differed. Interventions included:

diet and/or exercise intervention and/or behavioural counselling or weight monitoring versus standard care or routine care (Asbee 2009; Huang 2011; Jackson 2011; Jeffries 2009; Phelan 2011; Polley 2002; Vitolo 2011);
intensive exercise intervention (up to 85 sessions) versus routine care (Barakat 2011);
alternative interventions compared (low versus high glycaemic diet (Moses 2006); low glycaemic diet and exercise versus high glycaemic diet and exercise (Clapp 2002); three different exercise interventions (Clapp 2002a); group exercise and video versus diet and exercise information pack (Hui 2006); group nutrition education and computer assisted interview versus computer interview (Bechtel-Blackwell 2002); diet counselling with or without a probiotic supplement versus placebo (three arms) (Laitinen 2009).

Excluded studies

We excluded 12 studies. We excluded seven studies for the following reasons: participants included both pregnant and nonpregnant women (two studies); participants were not pregnant (postpartum or other non-pregnant participants) (four studies); or the intervention was not relevant (one study). The remaining five studies were not RCTs.

Risk of bias in included studies

Details of the methodological quality of each study are given in Characteristics of included studies, Figure 1, and Figure 2.

Allocation

Seventeen out of 27 included studies contributing data were assessed as being at low risk of bias for generation of the randomisation sequence and 12 used methods that we judged were at low risk of bias for allocation concealment. Three studies were assessed to use methods at high risk of bias for allocation concealment. The remaining studies were unclear for allocation concealment.

Blinding

Ten out of 27 studies had taken some steps to implement blinding. Acheiving blinding of treatment allocation for diet and exercise interventions is, however, not feasible and for most studies it was difficult to ascertain whether the lack of blinding, or unsuccessful blinding, impacted on outcomes or resulted in any systematic bias.

Incomplete outcome data

Fourteen of the studies either had relatively low levels of attrition or had carried out intention-to-treat analysis. Seven studies had a high rate of loss to follow-up. In the remaining studies, loss of outcome data was unclear.

Selective reporting

It was difficult to assess bias associated with the outcome reporting bias as we did not have access to study protocols and we did not know whether results for all outcomes where data had been collected had been reported; we therefore assessed most of these studies as being unclear for the outcome reporting bias.

Other potential sources of bias

We have reported in the Characteristics of included studies tables where we noted any obvious other sources of bias (such as clear differences between groups at baseline).

Effects of interventions

Our findings are based on data from 27 studies with 3964 women. Some studies had more than two arms and may have been included in more than one comparison and four studies reported data separately for high- and low-risk groups and relevant data have been included in more than one comparison. One study (Luoto 2011) was a cluster-randomised trial, and in the analyses we adjusted the sample size and event rates for this study by using an ICC from Luoto 2010. We have set out the original data from the Luoto 2011 study in Table 1 and Table 2.

Table 1. The original data and adjusted data of continuous data of the cluster-randomised trial (Luoto 2011).

Outcome	Intervention (Original data)			Control (Original data)			M¹	ICC²	Design effect³	Adjusted sample⁴ sizes

	Cluster number	Total number	x ± SD	Cluster number	Total number	x ± SD				Intervention	Control
Maternal	7	216	13.8±5.8	7	179	14.2±5.1	28.21	0.12	4.27	50.64	41.96
Weight gain

Study	Trimester	CASI plus nutrition education		CASI plus standard nutrition counselling		F	P value
		n	Mean weight gain (lb.)	n	Mean weight gain (lb.)	6.13	0.0000
Bechtel-Blackwell 2002	1	17	3.20	18	6.27	6.13	0.0000
	2	22	14.51	24	14.88	2.33	0.056
	3	22	15.14	24	12.29	3.44	0.0060

Study	Diethylpropion hydrochloride			Placebo
	n	Duration of therapy (weeks)	Average weight change (lb.)	n	Duration of therapy (weeks)	Average weight change (lb.)
Silverman 1971	28	10.9	6.97	9	10.9	8.78
Boileau 1968	52	13.0	1.2	53	12.9	7.0

Methods	Randomised controlled trial, set in resident obstetric clinic in Charlotte, North Carolina, USA
Participants	Inclusion criteria: prenatal care established at 6-16 weeks of gestation, age 18-49 years, all prenatal care received at the Resident Obstetrics Clinic, English-speaking, Spanish-speaking, or both, and singleton pregnancy Exclusion criteria: BMI higher than 40, pre-existing diabetes, untreated thyroid disease, or hypertension requiring medication or other medical conditions that might affect body weight, delivery at institution other than Carolinas Medical Center Main, pregnancy ending in premature delivery (less than 37 weeks), and limited prenatal care (fewer than 4 visits)
Interventions	Intervention group (n = 57) received consistent program of dietary and lifestyle counselling. At the initial visit, participants met with a registered dietician to receive a standardised counselling session, including information on pregnancy-specific dietary and lifestyle choices. The counselling consisted of recommendations for a patient-focused caloric value divided in a 40% CHO, 30% protein, and 30% fat fashion. Patients were instructed to engage in moderate-intensity exercise at least 3 times per week and preferably 5 times per week. They also received information on the appropriate weight gain during pregnancy using the IOM guidelines. Each participant met with the dietician only at the time of enrolment. At each routine obstetrical appointment, the healthcare provider informed the participant whether her weight gain was at the appropriate level. If her weight gain was not within the IOM guidelines, the participant’s diet and exercise regimen were reviewed and she was advised on increasing or decreasing her intake and increasing or decreasing exercise Control group (n = 43) received routine prenatal care, including an initial physical examination and history, routine laboratory tests, and routine visits per American College of Obstetricians and Gynecologists standards. The only counselling on diet and exercise during pregnancy was that included in a standard prenatal booklet. The healthcare provider did not counsel the participant regarding any changes in diet or lifestyle
Outcomes	Weight gain, caesarean delivery, pre-eclampsia, shoulder dystocia Total weight gain was defined as weight just before delivery minus prepregnancy weight
Notes	Age (intervention, control): 26.7 ± 6.0, 26.4 ± 5.0. Enrollment gestational age (intervention, control): 13.7 ± 3.6, 13.6 ±.2 weeks Prepregnancy BMI: 25.5 ± 6.0, 25.6 ± 5.1 kg/m^2. BMI category, n (intervention, control) underweight and normal weight (BMI < 26): 35, 25; overweight (BMI 26-29.0): 10, 8; obese (BMI > 29.0): 12, 10.
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation was performed using computer-generated random allocation
Allocation concealment (selection bias)	Low risk	Study allocation was concealed in numbered and sealed opaque envelopes
Blinding (performance bias and detection bias) All outcomes	Unclear risk	No information provided.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow-up reported. Trial authors stated that they had carried out an intention-to-treat analysis: data were analysed for participants according to their randomly-allocated group; all participants were included in the analysis
Selective reporting (reporting bias)	Low risk	The outcomes reported as in the published protocol.
Other bias	Low risk	Demographic data were similar. Age, prepregnancy weight, height and BMI were not different at baseline No other obvious bias.

Methods	Randomised controlled trial, set in Hospital de Fuen-labrada, Madrid, Spain
Participants	80 women randomised. Inclusion criteria: healthy pregnant women (age, 23-38 years), had uncomplicated, singleton pregnancies Exclusion criteria: any type of absolute obstetric contraindication to aerobic exercise during pregnancy, which included other contraindications that the authors considered to have a relevant influence on maternal perception of health: significant heart disease, restrictive lung disease, incompetent cervix/cerclage, multiple gestation, risk of premature labour, pre-eclampsia/pregnancy-induced hypertension, thrombophlebitis, recent pulmonary embolism (last 5 years), acquired infectious disease, retarded intrauterine development, serious blood disease, and/or absence of prenatal care
Interventions	Intervention group: (40 randomised) moderate physical activity, included a total of 35- to 45-minute weekly sessions 3 days each week from the start of the pregnancy (weeks 6-9) to the end of the 3rd trimester (weeks 38-39), an average of 85 training sessions, exercise intensity was light-to-moderate. Exercise was supervised by a fitness specialist and was in groups of 10-12 women Control group: (40 randomised) routine care.
Outcomes	Weight gain, caesarean, birthweight < 4000 gm, birthweight > 4000 gm
Notes
*Risk of bias*
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomly assigned by use of a random number table.
Allocation concealment (selection bias)	Unclear risk	Not described.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Not mentioned. It would be difficult to blind women and staff to this type of intervention. It is not clear how lack of blinding would impact on the outcomes measured
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	80 women were randomised and 67 were analysed; 34 in the exercise group, 33 in the control group. Reason of discontinued were similar in both groups
Selective reporting (reporting bias)	Unclear risk	Assessment from published study report.
Other bias	Unclear risk	No between-group differences regarding potential confounding variables (such as occupational activities, standing, smoking habits, alcohol intake). Parity was not balanced between groups; the exercise group had a higher percentage of nulliparous women (76.5%) than the control group (36.4%)

Methods	A prospective, quasi-experimental design, set in an adolescent prenatal clinic in USA
Participants	Adolescent African American women aged 13-18 years were recruited during 1 st trimester or early 2nd trimester
Interventions	Intervention group (n = 22): the nutrition education intervention consisted of 3 20-minute group sessions that addressed nutritional needs specific to the women’s stage of pregnancy Control group (n = 24): standard care for nutritional counselling Both groups received a nutrition assessment using a computer-assisted self-interview in 1st, 2nd, and 3rd trimesters
Outcomes	Weight gain, weight retention at 6 weeks’ postpartum.
Notes	The data of weight gain were reported in terms of weight gain during the 1 st, 2nd and 3rd trimester with no SDs reported
*Risk of bias*
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Participants were randomly assigned to groups.
Allocation concealment (selection bias)	High risk	Quasi-randomisation.
Blinding (performance bias and detection bias) All outcomes	Low risk	Group members would be unable to distinguish who was in the experimental group
Incomplete outcome data (attrition bias) All outcomes	High risk	Loss to follow-up 23%; 26% in intervention group, 20% in control group Not provided information on reasons for loss to follow-up.
Selective reporting (reporting bias)	Unclear risk	Could not determine.
Other bias	Low risk	Maternal background characteristics revealed no statistically significant differences between groups

Methods	Randomised controlled trial, place of study not stated.
Participants	Private patients in the 2nd trimester who were accumulating weight more rapidly and appeared to be excessively overweight at the beginning of pregnancy. Exclusion criteria were not reported
Interventions	Intervention (n = 53): diethylpropion hydrochloride, 75 mg. Control (n = 53): placebo.
Outcomes	Weight change at each stage of gestation.
Notes	No SD for mean outcomes were reported. Age (intervention, control): 26.3, 26.4. Enrollment gestational age (intervention, control): 25, 25 weeks BMI before pregnancy (intervention, control): 25.3, 23.8 kg/m².
*Risk of bias*
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No information provided.
Allocation concealment (selection bias)	Unclear risk	No information provided.
Blinding (performance bias and detection bias) All outcomes	Low risk	Neither the investigators nor the patients knew the content of the bottle
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Could not determine.
Selective reporting (reporting bias)	Unclear risk	Could not determine.
Other bias	Low risk	Baseline data showed the 2 groups were comparable.

Methods	Randomised controlled trial, set in a hospital in Brisbane, Australia
Participants	50 women randomised. Inclusion criteria: obese pregnant women were recruited at 12 weeks’ gestation, aged 18-45, BMI ≥ 30 kg/m², pregnancy care at study hospital, willing and able to be randomised to an exercise intervention Exclusion criteria: non-English speaking, contraindication or inability to exercise, medical or obstetric contraindication to exercise including haemodynamically significant heart disease, restrictive lung disease, incompetent cervix (cerclage), multiple gestation, severe anaemia, chronic bronchitis, type 1 diabetes, orthopaedic limitations, poorly controlled seizure disorder, poorly controlled hyperthyroidism, or a heavy smoker
Interventions	Intervention group: the intervention group received an individualised exercise program with an energy expenditure (EE) goal of 900 kcal/ week. Advice from physiotherapist and diaries for self-monitoring Control group: routine obstetric care.
Outcomes	Self-report of exercise (behaviour change).
Notes
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation was by a random number allocation technique conducted by a 3rd party
Allocation concealment (selection bias)	Unclear risk	Not clear but external randomisation.
Blinding (performance bias and detection bias) All outcomes	High risk	No blinding.The impact of the lack of blinding was not clear. The use ofself-monitoring diaries by the intervention group may have introduced recall bias
Incomplete outcome data (attrition bias) All outcomes	High risk	Randomised 50 women, at 36 weeks 36 were followed up (30% attrition)
Selective reporting (reporting bias)	Unclear risk	Assessment from published study report and on-line supplement
Other bias	Unclear risk	There were no statistically significant differences between the intervention and control groups in any baseline variable. Different monitoring techniques in the 2 groups (diaries in the intervention group) may have led to recall bias

Methods	A prospective randomised design.
Participants	20 healthy women with uncomplicated pregnancy.
Interventions	The participants were enrolled prior to pregnancy and placed on a regular regimen of supervised exercise and began a weight maintaining diet (low glycaemic sources of CHO) . At 8 weeks’ gestation, they were randomised to either diet containing low glycaemic CHO sources(n =10) (aboriginal CHO diet) or high glycaemic CHO sources (n = 10) (cafeteria CHO diet). All continued the same exercise regimen throughout pregnancy
Outcomes	Weight gain. Total weight gain was defined as weight at delivery minus prepregnancy weight
Notes	During pregnancy, all women were allowed to increase caloric intake according to appetite with advancing gestation
*Risk of bias*
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described.
Allocation concealment (selection bias)	Unclear risk	No information provided.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	No information provided.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Unspecified loss to follow-up.
Selective reporting (reporting bias)	Unclear risk	No information provided.
Other bias	Unclear risk	No information provided.

Methods	Randomised controlled trial, set in Case Western Reserve University at metro health medical centre, USA
Participants	Inclusion criteria: 80 healthy, regularly exercising (≥ 3 times/week), non-substance-abusing women were enrolled before pregnancy After conception (which occurred within 4 months in all cases) and ultrasonic confirmation of a viable singleton pregnancy, these women were assigned in week 8 of gestation to the exercise regimens Exclusion criteria: not stated. Number of participants: 75 women enrolled and complete the protocol; 26 in Lo-Hi group, 24 in Mod-Mod group, 25 in Hi-Lo group
Interventions	There were 3 study groups: group 1: low-high exercise (n = 26): exercise 20 minutes 5 days a week through to week 20, gradually increasing to 60 minutes 5 days a week by week 24 and maintaining that regimen until delivery (Lo-Hi) group 2: moderate-moderate exercise (n = 24): exercise 40 minutes 5 days a week from week 8 until delivery (Mod-Mod) group 3: high-low exercise (n = 25): exercise 60 minutes 5 days a week through to week 20, gradually decreasing to 20 minutes 5 days a week by week 24 and maintaining that regimen until delivery (Hi-Lo)
Outcomes	Weight gain.
Notes	Age 31 ± 1, 30 ± 1, 32 ± 1 in Lo-Hi, Mo-Mo, Hi-Lo.
*Risk of bias*
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Women were randomly assigned.
Allocation concealment (selection bias)	Unclear risk	Women were randomly assigned by envelope but it was not stated whether envelopes were sequentially numbered, opaque and sealed.
Blinding (performance bias and detection bias) All outcomes	High risk	A member of the study team carried out morphometric assessment of placenta and infant at the time of birth.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Loss to follow-up 6.25%.
Selective reporting (reporting bias)	Unclear risk	Could not determine.
Other bias	Low risk	Baseline data were similar.

Methods	Randomised controlled trial, set in the prenatal clinic, University Hospital of Leuven, Belgium
Participants	Inclusion criteria: obese (BMI > 29.0 according to IOM criteria), white women consecutively attending the prenatal clinic before 15 week of gestation Exclusion criteria: preexisting diabetes or developing GDM, multiple pregnancy, recruitment after 15 week of gestational age, premature labour (delivery before 37 week of gestation), primary need for nutritional advice in case of a metabolic disorder, kidney problems, Crohn’s disease, allergic conditions, and inadequate knowledge of the Dutch language
Interventions	2 intervention groups: the passive group (n = 37): received a brochure during the 1st prenatal consultation. This brochure was specifically designed for the study and provided advice on nutrition and on physical activity and tips to limit pregnancy-related weight gain. The active group (n = 42): received the same brochure and women were actively counselled by a trained nutritionist in 3 group sessions. A maximum of 5 women were brought together in these 1-hour sessions, which were scheduled at 15, 20, and 32 weeks of pregnancy. The sessions provided subjects with recommendations on a balanced, healthy diet, based on the Official National Dietary Recommendations (9-11% of the energy should come from proteins, 30-35% from fat, and 50-55% from CHOs) Control group (n = 43): received routine prenatal care. (Energy intake was not restricted in any group.)
Outcomes	Excessive weight gain (weight gain more than the upper limit recommendation for overweight women; >11.2 kg) Gestational weight gain. Obstetrical and neonatal outcome: pre-eclampsia, induction oflabour, caesarean section, birthweight > 4000 gm Average energy intake. Weight gain was defined as weight at birth minus prepregnancy weight Total physical activity score at 3rd trimester. For analysis 3.10 and 4.10 a physical activity score was calculated by using a questionnaire including a total 16 questions classified into 3 domains: work, sports, and non-sports leisure-time activities, scored on a 5-point scale, ranging from “never”, “seldom”, “sometimes”, “very often”, to “always”. A total score for physical activity from a minimum of 3 to a maximum of 15 was obtained. A higher score indicated more activity
Notes	Age 29.4 ± 4.4, 28.7 ± 4.0, 28.0 ± 3.6 years for control group, passive group, active group Enrollment gestational age: 10.2 ± 2.4, 10.2 ± 2.6, 9.3 ± 2.8 weeks for control group, passive group, active group Prepregnancy BMI: 33.5 ± 3.9, 33.4 ± 3.07, 34.1 ±4 .5 kg/m² for control group, passive group, active group.
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No information provided.
Allocation concealment (selection bias)	Low risk	Patients were randomly assigned by using block randomisation
Blinding (performance bias and detection bias) All outcomes	Unclear risk	No information provided.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Loss to follow-up 9.7%. Reasons for excluding the participants from each group were similar
Selective reporting (reporting bias)	Unclear risk	Could not determined.
Other bias	Low risk	Baseline characteristics ofparticipants were similar between intervention and control groups

Methods	Randomised controlled trial; 3 groups intervention design; 2 experimental groups (from pregnancy to 6 months postpartum (EP) and from birth to 6 months postpartum (EPP). The group receiving the intervention in the postnatal period only is not included in our analysis) and 1 comparison group
Participants	From January to June 2006, pregnant women were recruited from the obstetric clinics of a hospital in Taiwan. (160 women randomised.) Inclusion criteria: 16 gestational weeks, age 18 years or older, no cognitive impairment or psychiatric illness, ability to speak and read Chinese, not participating in another study, and intention to give birth at the study site
Interventions	Intervention group: (80 participants).The educational intervention began at 16 gestational weeks (baseline) and to 6 months postpartum. The intervention was delivered at regularly scheduled clinic visits by nurses with training in nutrition and physical fitness. The nurse discussed with each participant how to design an individualised diet and physical activity plan. The intervention consisted of 6 1-to-1 counselling sessions: 1 primary session (about 30-40 minutes) at the 16-week gestation visit, and 5 1-to-1 booster sessions (at 28 gestational weeks, 36-38 gestational weeks, before hospital discharge after a 3-7-day stay, 6 weeks’ postpartum and 3 months postpartum). After each clinic visit, women in the experimental groups were sent a personalised graph of their weight changes. At the 1st session, the experimental groups also received a researcher-prepared brochure that provided detailed information on weight management goals during pregnancy and postpartum Control group: (80 participants) routine care, provided once each trimester which health education on nutrition and exercise during pregnancy
Outcomes	Gestational weight gain, weight retention at 6 months postpartum, health-promoting behaviour; physical activity For analysis 1.9.1 physical activity measurement was a part of the health-promoting lifestyle profile composed of 50-item scale uses a 4-point response format (range = 50200) to measure the frequency of engaging in activities related to self-actualisation, nutrition, physical activity,interpersonal support, health responsibility and stress management
Notes
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Using a table of random numbers.
Allocation concealment (selection bias)	Unclear risk	Not stated.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	The research assistant collecting outcome data was reported to be blind to the group assignments
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	80 women in each group were randomised, 61 and 64 of intervention and control group were analysed (78% followed up)
Selective reporting (reporting bias)	Unclear risk	Assessment from published study report.
Other bias	Low risk	No notable baseline differences were found between groups.

Methods	Randomised controlled trial, set in a community nurse-managed centre and the Manitoba Clinic, both in urban Winnipeg, Manitoba, Canada
Participants	Inclusion criteria: women < 26 weeks pregnant with no pre-existing diabetes were recruited on a voluntary basis. Exclusion criteria: pregnant women who had medical obstetric, skeletal or muscular disorders that could contraindicate physical exercise during pregnancy
Interventions	Intervention (n = 24): additional intervention: lifestyle intervention including exercise intervention and dietary intervention Exercise intervention: participants were instructed in group-session exercises and in home-based exercise. Weekly group session included floor aerobics, stretching and strength exercises, 3-5 times/week for 30-45 minutes per session, video provided to participants to assist with home-based exercise Nutrition intervention: computer-assisted food choice map interview, dieticians provided a personalised plan for participants Control (n = 21): standard care group received an information package on diet and physical activity for a healthy pregnancy
Outcomes	Excessive weight gain, weight gain, cesarean section, infant birthweight > 4000 gm, and physical activity at end of study Weight gain was defined as weight at birth (from medical chart) minus prepregnancy weight For analysis 1.9.1 physical activity was defined as recreational physical activity which was measured by using the PARmed-X for Pregnancy form based on Health Canada recommendations. Low levels (physical activity = 0) are defined as either no physical activity or activity < 1 to 2 times per week and for < 20 min per session; moderate levels (physical activity = 1) are defined as activity 1 to 2 times per week and for > 20 min per session or > 2 times per week and for < 20 min per session; high level (physical activity = 2) are defined as activity > 2 times per week and for > 20 min per session
Notes	Age (intervention, control): 26.2 ± 5.7, 26.2 ± 5.4. Prepregnancy BMI (intervention, control): 25 ± 6.3, 23.4 ± 3.9 kg/m² Excessive weight gain was assessed based on prepregnant BMI. BMI < 20 kg/m², weight gain during pregnancy 12.5 -18 kg. BMI 20-27 kg/m², upper limit of weight gain 16 kg. BMI > 27 kg/m², upper limit of weight gain 11.5 kg. (Canadian guidelines for healthy weights.) Majority of participants (89%) were from low-income families or low-middle income families
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Participants were enrolled and randomised into additional intervention and standard care groups
Allocation concealment (selection bias)	Unclear risk	No information provided.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	No information provided.
Incomplete outcome data (attrition bias) All outcomes	High risk	52 enrolled, 45 completed. Loss = 7/52*100 = 13.5%. 7 pregnant women dropped out due to school or work commitments The participants who dropped out were significantly younger and had lower incomes than those who completed the program (P < 0.01)
Selective reporting (reporting bias)	Unclear risk	Could not determine.
Other bias	Low risk	No significant differences were found in age, prepregnancy BMI, and family income between additional intervention and standard care groups

Methods	Randomised controlled trial, set in 5 prenatal care practices in the San Francisco Bay Area, USA, including 3 public hospitals, 2 academic practices, and a community hospital. 2006-2007
Participants	327 women randomised. Inclusion criteria: English-speaking women 18 years or older and less than 26 weeks of gestation Exclusion criteria: women who report smoking, alcohol use, drug use, or partner violence
Interventions	Intervention group: (163 randomised) The Video Doctor: an interactive computer program including in-depth behavioural risk assessments and tailored counselling messages, and producing printed output for both the patient and clinician. An actor-portrayed Video Doctor appears and offers education on exercise, nutrition and weight gain based on principles of Motivational Interviewing. Dietary counselling focused on increasing intake of fruits and vegetables and whole grains, increasing healthful versus unhealthful fats and decreasing sugary foods. The Video Doctor emphasised dietary and exercise behaviour changes over weight gain. The Video Doctor programme required 10-15 minutes to complete. After 4 weeks, participants received a brief “booster” Video Doctor counselling Control group: (164 randomised) usual care. The usual care group did not interact with the Video Doctor and the program did not produce a Cueing Sheet or Educational Worksheet. Behavioural counselling for the usual care group was determined by the clinician
Outcomes	Self-reported servings per day or week of healthful foods (e.g. fruits and vegetables) and unhealthful foods (e.g. sweets), and exercise duration and frequency, and weight gain above the IOM guidelines
Notes
*Risk of bias*
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation by computer.
Allocation concealment (selection bias)	Low risk	Randomisation by computer (interactive computer programme intervention)
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Participants would not be blind to the intervention. It was not stated that staff or outcome assessors were blinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	6 women were excluded after randomisation: 3 due to insufficient English, 1 because of inaccurate gestational age, and 2 withdrew during the baseline assessment leaving 158 in the Video Doctor group and 163 in the usual care group. Intention-to-treat analysis was performed for primary outcome (weight gain) for other outcomes 327 were randomised and 287 (88%) completed follow-up
Selective reporting (reporting bias)	Unclear risk	Assessment from published study report.
Other bias	Unclear risk	There were no significant differences between the control and Video Doctor groups for any of the demographic variables listed except education. Results for weight gain were not fully reported by randomisation group. Results for mean weight gain of each group were reported without SDs

Methods	Randomised controlled trial, set in a tertiary obstetric hospital in Melbourne, Australia
Participants	Inclusion criteria: pregnant women at < 14 weeks’ gestation. Exclusion criteria: age < 18 or > 45 years, type 1 or type 2 diabetes mellitus, multiple pregnancy, or non-English speaking
Interventions	Intervention (n = 125): women allocated to the intervention group were given a personalised weight measurement card, advised of their optimal gestational weight gain (based on their BMI at the time of recruitment and the United States IOM guidelines, and instructed to record their weight at 16, 20, 24, 28, 30, 32 and 34 weeks’ gestation Control (n = 111): not given instructions about regular weight measurement
Outcomes	Weight gain above IOM guideline, mean weight gain from recruitment to follow-up at 36 weeks’ gestation Small-for-gestational age (< 10th centile), large-for-gestational age (> 90th centile), preterm (< 37 weeks), instrumental delivery, caesarean delivery, pre-eclampsias, neonatal hypoglycaemia, shoulder dystocia Weight gain was weight difference between weight at about 36 weeks’ gestation and weight at 1st antenatal appointment
Notes	Gestation age at recruitment (intervention, control): 11.6, 11.4 weeks BMI category, n (intervention, control): underweight (BMI ≤ 19.8): 5, 5; normal (BMI >19.8, ≤ 26.0): 75, 67; overweight (BMI > 26, ≤ 29.0): 20, 18; obese (BMI > 29.0): 25, 21.
*Risk of bias*
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Using computer random number generation.
Allocation concealment (selection bias)	Low risk	Using opaque, sequentially numbered envelopes.
Blinding (performance bias and detection bias) All outcomes	Low risk	All participants were blinded to the purpose of the study.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Loss to follow-up, 23/148 in intervention group, 27/138 in control group Similar reason of loss to follow-up in intervention and control groups
Selective reporting (reporting bias)	Low risk	The outcomes reported as in the published protocol.
Other bias	Low risk	Baseline characteristics were similar.

Methods	Randomised controlled trial, set in 2 hospitals in rural municipalities (Kauha-joki and Lapua) in Finland
Participants	60 women randomised. Inclusion criteria: women at high risk of gestational diabetes: women had 1 or more risk factors (BMI > 25 kg/m2, previous history of GDM or birth of child > 4.5 kg, age > 40 years, family history of diabetes or the venous plasma glucose concentration after 12 hours fasting in the morning was 4.8-5.5 mmol/L and 2-hour OGTT plasma glucose < 7.8 mmol/L Exclusion criteria: women who were diagnosed as having GDM in this study and women who had risk factors for GDM or whose fasting venous plasma glucose was 4.8-5.5 mmol/L but who for personal or professional reasons did not wish to participate in the trial
Interventions	Intervention group: (n = 30) a lifestyle intervention; included diet counselling and exercise counselling. Dietary advice tailored to each subject individually on 6 occasions. Women were encouraged to eat a diet rich in vegetables, berries and fruits, and to use low-fat. Moderate-intensity physical exercise during pregnancy was encouraged, 6 sessions for exercise counselling Control group: close follow-up group (n = 30). All women were given general information on diet and physical activity to decrease the risk of GDM during pregnancy as part of routine care
Outcomes	Weight gain.
Notes
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Women were randomly assigned to the lifestyle intervention group or to the close follow-up group by the study physician in the Central Hospital with the use of a computed randomisation list
Allocation concealment (selection bias)	Unclear risk	Not stated.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Women would be aware of group assignment although it was stated that the nurses scheduling study visits did not have access to the randomisation list. It is not clear what impact the lack of blinding would have on the outcomes measured
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	60 women were randomised, 54 were followed up.
Selective reporting (reporting bias)	Unclear risk	Assessment from published study report.
Other bias	Unclear risk	There were no statistically significant differences in baseline measures between the lifestyle intervention and the close follow-up groups although women in the intervention group had slightly higher prepregnancy weight (mean 76.6 compared with 69.6 in controls

Methods	Randomised controlled trial, set in maternal welfare clinics in the city of Turku and neighbouring areas in south-west Finland
Participants	Women were eligible for participation if they were less than 17 weeks’ gestation and had no metabolic or chronic diseases such as diabetes Participants were Caucasian.
Interventions	At 1st trimester 256 pregnant women were allocated to 3 groups: modification of dietary intake according to current recommendations with probiotics or placebo and a control group receiving placebo only Control group, (placebo) (n = 85). Intervention group 1 (n = 86) (diet counselling and placebo). Intervention group 2 (n = 85) (diet counselling and probiotics), probiotic capsules containing Lactobacillus rhamnosus GG and Biﬁdobacterium lactis Bb12. Dietary counselling given by a dietitian at each study visit aimed to modify dietary intake to conform with that currently recommended, particular attention being paid to the quality of dietary fat Study visits took place 3 times during pregnancy at 13·9 (SD 1·6), 23·8 (SD 1·4) and 33·9 (SD 1·4) weeks of gestation and at 1, 6 and 12 months postpartum
Outcomes	Weight gain, energy intake, dietary fibre intake at 3rd trimester of pregnancy Weight gain was calculated by subtracting self-reported prepregnancy weight from that recorded at a prenatal visit or at hospital within 1 week before delivery
Notes	Age (intervention 1, intervention 2, control): 30.1 ± 5.2, 29.7 ± 4.1, 30.2 ± 5.0
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Subjects were randomly assigned to 3 study groups according to computer-generated block randomisation
Allocation concealment (selection bias)	Low risk	Using sealed envelopes. At the 1st study visit the envelopes were opened. The random allocation sequence was thus concealed until interventions were assigned
Blinding (performance bias and detection bias) All outcomes	Low risk	Intervention groups took place in a double-blind manner, while the control group received placebo in single-blind manner
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow-up (to delivery).
Selective reporting (reporting bias)	Low risk	The outcomes reported as in the published protocol.
Other bias	Low risk	No other bias apparent.

Methods	Cluster-randomised controlled trial, set in primary healthcare centres in 14 municipalities in Pirkanmaa region in south-western Finland
Participants	Recruitment 2007-8. Inclusion criteria: Pregnant women at 8-12 weeks’ gestation at high risk of developing gestational diabetes; BMI ≥ 25 kg/m² based on measured height and self-reported prepregnancy weight; GDM or any signs of glucose intolerance or newborn’s macrosomia (≥ 4500 gm) in any earlier pregnancy; type 1 or 2 diabetes in 1st- or 2nd-degree relatives; or age ≥ 40 years Exclusion criteria: at least 1 of the 3 baseline (8-12 weeks’ gestation) OGTT measurements was abnormal (fasting blood glucose ≥ 5.3 mmol/L, 10.0 mmol/L at 1 hr, and 8.6 mmol/L at 2 hr); prepregnancy type 1 or 2 diabetes; inability to speak Finnish; age <18 yr; multiple pregnancy; physical restriction preventing physical activity; substance abuse; treatment or clinical history of psychiatric illness
Interventions	Intervention group: (7 municipalities) Individual counselling on physical activity and diet and weight gain. At the 1st visit the recommendations for gestational weight gain were discussed and an appropriate weight gain graph was selected to guide the participant in monitoring her weight gain. The primary physical activity counselling was implemented at 8-12 weeks’ gestation and the primary dietary counselling session at 16-18 weeks’ gestation. Physical activity counselling was enhanced at 4, and diet counselling at 3 subsequent visits Control group: (7 municipalities) usual care group received no counselling beyond usual care, which included some dietary counselling (partly on different topics) and follow-up of gestational weight, but little physical activity counselling
Outcomes	Incidence of GDM as assessed by OGTT (maternal outcome) and newborns’ birthweight adjusted for gestational age, maternal weight gain and the need for insulin treatment during pregnancy, changes in physical activity and diet (intake of total fat, saturated and polyunsaturated fatty acids, saccharose, and fibre
Notes
*Risk of bias*
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	The unit of randomisation was municipality. In the randomisation process, participating municipalities were 1st pair-wise matched. 14 municipalities were then randomised by computer
Allocation concealment (selection bias)	Low risk	Cluster-randomised trial with computer randomisation.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	The impact of lack of blinding in this trial is unclear. Women would be aware of intervention and so would staff. Women in the intervention group were provided with notebooks to record diet and activity, women in the control group were not; this may have affected recall and may have introduced bias. It was not clear whether staffcollecting outcome data were blind to group assignment
Incomplete outcome data (attrition bias) All outcomes	High risk	14 clusters were randomised and all were included in the analysis. 343 women in the intervention and 297 in the usual care group agreed to participate in the trial. However, 81 (23.6%) of the participants in intervention group and 93 (31.3%) of the participants in the usual care group had an abnormal OGTT result at baseline and were thus excluded. The final number of participants in the analyses was 219 (89. 0% of participants receiving allocated intervention) in the intervention group and 180 (91.8% of participants receiving allocated intervention) in the usual care group. However about 40% of eligible participants of each group were followed up
Selective reporting (reporting bias)	Unclear risk	Assessment from published study reports.
Other bias	Unclear risk	Baseline characteristics of each group were similar, except there were women in the intervention group with high education than in the usual care group. There was adjustment of data for clustering and various cluster, clinic and individual level differences at baseline

Methods	Randomised controlled trial, set in prenatal care at the University of Washington Obstetrics Clinics
Participants	Pregnant women with obesity (prepregnancy weight > 120% of ideal body weight) and diagnosed with gestational diabetes, recruited at 28 weeks’ gestation
Interventions	All patients were hospitalised for 2-week duration in the metabolic ward Intervention; calorie-restricted (n = 7): during the 1st week, the women consumed normal diet with 2400 kcal/day; 50% CHO, 30% fat and 20% protein with 11 gm of total dietary fibre per 500 kcal. During the 2nd week, the women were placed on 1200 kcal/day diet. This reduction was accomplished by decreasing portion sizes without changing other features of diet Control (n = 5): during the 1st week, the patients consumed identical diet as the intervention group; 2400 kcal/day, and continued on the same diet (2400 kcal/day) during the 2nd week
Outcomes	Metabolic indices: fasting plasma glucose, OGTT, insulin, triglyceride, free fatty acids, glycerol, ß-hydroxybutyrate, and urine ketones We have not included outcome data from this hospital inpatient study in the analyses in the review
Notes	Age (calorie-restricted, control): 30 ± 4, 36 ± 5 years.
*Risk of bias*
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No information provided.
Allocation concealment (selection bias)	Unclear risk	No information provided.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	No information provided.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No information provided.
Selective reporting (reporting bias)	Unclear risk	Could not determine.
Other bias	Unclear risk	No information provided.

Methods	Quasi-randomised controlled trial, set in antenatal clinic at Wollongong Hospital, Wollongong, NSW, Australia
Participants	Inclusion criteria: healthy, pregnant women from the antenatal clinic at Wollongong Hospital and from 2 obstetricians in private practice. They were aged 21- 40 years, had a singleton pregnancy, were between 12 and 16 weeks’ gestation, were nonsmokers, and consumed no more than 1 alcoholic drink each day Exclusion criteria: any problem associated with glucose metabolism or insulin resistance or that interfered with the ability of the study participant to follow dietary instructions
Interventions	Participants were randomised to a low glycaemic diet or high glycaemic diet Low glycaemic diet (n = 32): seen by dietitian 5 times during pregnancy, received dietary recommendation for low GI diet with 33% fat, 55% CHO. The low GI diet was based on verified low-GI foods, including pasta and brand-name breads and breakfast cereals with a high fibre content High glycaemic diet (n = 30): also seen by dietitian 5 times during pregnancy, received dietary recommendation for moderate-to-high GI diet (high fibre, low sugar) with 33% fat, 55% CHO
Outcomes	Weight gain (from 12 weeks to 36 weeks), large-for-gestational age (>90th centile for birthweight), small-for-gestational age (< 10th centile for birthweight)
Notes	Age (low GI, high GI): 30.1 ± 0.7, 29.6 ± 0.7. BMI at baseline (low GI, high GI): 24.4 ± 0.7, 26.6 ± 0.9 kg/m² The baseline visit was between 12-16 weeks’ gestation.
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Alternation.
Allocation concealment (selection bias)	High risk	Alternate allocation to study groups.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	No information provided.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Loss of participants to follow-up: In the low-GI diet group, 2 women withdrew due to being unwilling to follow the diet and 1 delivered before the final visit. In high-GI diet group, 1 woman was unwilling to follow the diet, 1 lost to follow-up, and 3 miscarriages Intention-to-treat analysis: data were analysed for participants according to their randomly-allocated group, not all original participants were included in the analysis
Selective reporting (reporting bias)	Unclear risk	Could not determine.
Other bias	Low risk	Baseline characteristics were similar.

Methods	Randomised controlled trial, 2 arms with individual randomisation (stratified by prepregnancy weight, set in 6 obstetric of ces in Providence, Rhode Island, USA from 2006 to 2008
Participants	401 women randomised. Inclusion criteria: gestational age between 10 and 16 weeks, BMI between 19.8 and 40, nonsmoking , adults (aged > 18 yr), influency in English, access to a telephone, and a singleton pregnancy Exclusion criteria: major health or psychiatric diseases, weight loss during pregnancy, or a history of ≥ 3 miscarriages
Interventions	Intervention group: standard care plus a behavioural lifestyle intervention. The Fit for Delivery intervention included a face-to-face visit with an interventionist at the onset of treatment who discussed appropriate weight gains during pregnancy, physical activity (30 min of walking most days of the week), and calorie goals (20 kcal/kg); emphasis was placed on decreasing high fat foods, increasing physical activity, and daily self-monitoring of eating, exercise, and weight. Body-weight scales, food records, and pedometers were provided to promote adherence to daily self-monitoring. Automated postcards that prompted healthy eating and exercise habits were mailed weekly. In addition, after each clinic visit, women were sent personalised graphs of their weight gains with feedback. All women in the intervention received 3 brief (i.e., 10-15 min) supportive phone calls from the dietitian during the intervention. Women who were over or under weight-gain guidelines during any 1 month interval received additional brief, supportive phone calls (2 calls/mo) that provided structured meal plans, and specific goals until weight gains returned to appropriate amounts Control group: routine care. Women received standard nutrition counselling provided by physicians, nurses, nutritionists, and counsellors. As part of routine care women were weighed by nurses at each clinical visit; weight graphs were not provided
Outcomes	Excessive weight gain, low weight gain, preterm birth, pre-eclampsia or eclampsia, caesarean delivery rate, high birthweight, low birthweight, maternal weight retention
Notes
*Risk of bias*
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation was computer-generated in randomly varying block sizes and stratified by clinic and BMI category
Allocation concealment (selection bias)	Low risk	Allocation was concealed in opaque envelopes prepared by the study statistician
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Unblinded study research coordinator enrolled and randomly assigned participants into groups. In the abstract it was stated that outcome assessors were blinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	Lost to follow-up 34 in the standard care group, 36 in the intervention group. Exclusions: 18 in the standard care group, 25 in the intervention group 401 participants were randomly assigned into the intervention (n = 201) and control groups ( n = 200), included in 6 month postpartum analysis; 182 control, 176 intervention ITT analysis was performed assuming that those lost to follow-up were treatment failures. It was reported that this revealed almost identical results as for those completing the study (data not shown)
Selective reporting (reporting bias)	Unclear risk	Assessment from published study report.
Other bias	Unclear risk	The 2 study groups did not significantly differ on key baseline measures (sample stratified)

PERMALINK

Interventions for preventing excessive weight gain during pregnancy

Benja Muktabhant

Pisake Lumbiganon

Chetta Ngamjarus

Therese Dowswell

Abstract

Background

Objectives

Search methods

Selection criteria

Data collection and analysis

Main results

Authors’ conclusions

BACKGROUND

Description of the condition

Pregnancy weight gain guidelines

Trends in pregnancy weight gain

Pregnancy weight gain and outcomes for mothers and infants

Description of the intervention

How the intervention might work

Why it is important to do this review

OBJECTIVES

METHODS

Criteria for considering studies for this review

Types of studies

Types of participants

Types of interventions

Types of outcome measures

Primary outcomes

Secondary outcomes

For the mothers

For the newborns

Long-term health outcomes

Search methods for identification of studies

Electronic searches

Data collection and analysis

Selection of studies

Data extraction and management

Assessment of risk of bias in included studies

Measures of treatment effect

Unit of analysis issues

Dealing with missing data

Assessment of heterogeneity

Assessment of reporting biases

Data synthesis

Subgroup analysis and investigation of heterogeneity

Sensitivity analysis

RESULTS

Description of studies

Results of the search

Included studies

Excluded studies

Risk of bias in included studies

Figure 1. Methodological quality summary: review authors’ judgements about each methodological quality item for each included study.

Figure 2. Methodological quality graph: review authors’ judgements about each methodological quality item presented as percentages across all included studies.

Allocation

Blinding

Incomplete outcome data

Selective reporting

Other potential sources of bias

Effects of interventions

Table 1. The original data and adjusted data of continuous data of the cluster-randomised trial (Luoto 2011).

Table 2. The original data and adjusted data for dichotomous data of the cluster-randomised trial (Luoto 2011).

1. Interventions to prevent excessive weight gain versus standard care or routine care (interventions in general population groups) (nine trials)

Primary outcome

1.1 Excessive weight gain

Secondary outcomes

For the mothers

1.2 Weight gain

1.3 Low weight gain

1.4 Preterm birth

1.5 Pre-eclampsia

1.6 Need for and indication for induction of labour and caesarean delivery

1.7 - 1.10 Behaviour modification outcomes: diet, physical activity

For the newborns

1.11 - 1.14 High and low birthweight

1.15 - 1.16 Complication related to macrosomia

Long-term health outcomes

1.17 - 1.18 Maternal weight retention

Methods	Randomised controlled trial, set in an obstetric clinic for low-income women at a hospital in Pittsburgh, PA, USA
Participants	Inclusion criteria: pregnant women before 20 weeks of gestation. (Subjects were recruited in to 4 cells; normal and overweight, black and white.) Exclusion criteria: underweight women, younger than 18 years, 1st prenatal visit > 12 weeks’ gestation, high-risk pregnancy (i.e.. drug abuse, chronic health problems, previous complications during pregnancy, current multiple gestation)
Interventions	Intervention (n = 57): the intervention was provided at regular scheduled clinic visits by staff with training in nutrition or clinical psychology. Education about weight gain, healthy eating, and exercise and individual graphs of their weight gain Shortly after recruitment, written and oral information were given in the following area: appropriate weight gain, exercise, healthy eating.Newsletters prompting healthy eating and exercise habits were mailed bi-weekly. After each clinic visit, women were sent a personalised graph of their weight gain Those exceeding weight gain goals were given additional individualised nutrition and behavioural counselling using the format listed; a stepped care approach Control (n = 53): usual care: standard nutrition counselling provided by the physicians, nurses, nutritionists and WIC counsellors. This counselling emphasised a well-balanced dietary intake and advice to take a multivitamin/iron supplement
Outcomes	Excessive weight gain, total weight gain, low weight gain. Low birthweight infants, macrosomia infants, preterm delivery, caesarean delivery, pre-eclampsia, weight retention at 4 weeks’ postpartum Total weight gain was based on self-reported prepregnancy weight and weight at last clinic visit prior to delivery
Notes	Excessive weight gain categorised as above the IOM recommendations Low weight gain categorised as below the IOM recommendations IOM recommends a weight gain of 6.8-11.3 kg for overweight women (BMI of 26-29) and a weight gain of 6.8 kg (with no specified upper limit) for obese women (BMI > 29) Age of participants 25.5 ± 4.8. Gestational age at recruitment (intervention, control): 14.7 ± 3.1 weeks BMI category, n (intervention, control): normal weight (BMI19.8-26): 30, 31; overweight (BMI > 26): 27, 22.
*Risk of bias*
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Women were randomly assigned to the standard care control group or to the intervention
Allocation concealment (selection bias)	Unclear risk	No information provided.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	No information provided.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Using intention-to-treat approach. Loss to follow-up < 10%.
Selective reporting (reporting bias)	Unclear risk	Could not determine.
Other bias	High risk	Refusal rates were higher among black women (28/74 refused) than among white (16/90 refused), and higher in overweight black women than in any of the other 3 weight-by-race categories

Methods	Randomised controlled trial (pilot study), set in Beth Israel Deaconess Medical Center, Boston, MA, and Children’s Hospital Boston, Boston, MA, USA
Participants	Inclusion criteria: pregnant women with prepregnancy or 1st trimester BMI equal to or greater than 25 kg/m² and less than 45 kg/m², singleton pregnancy, willing to consume the diets for duration of pregnancy, participant to be at week 28 or less of pregnancy at baseline visit Exclusion criteria: smoking during pregnancy, major medical illness (e.g., diabetes mellitus, hypertension, thyroid disease), taking prescription medication known to affect body weight, alcohol consumption during pregnancy, intention to deliver infants in the environment outside of Beth Israel Deaconess MedicalCenter, Boston, high level of physical activity
Interventions	Intervention group 1: nutrition education, dietary counselling, and a low-GL diet Intervention group 2: nutrition education, dietary counselling, and a low-fat diet
Outcomes	Maternal outcome: weight change Infant outcome: macrosomia, large-for-gestational age, caesarean delivery
Notes
*Risk of bias*
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomly “permuted blocks of 2 and 4 preventing anticipation of future assignments
Allocation concealment (selection bias)	Low risk	Separate random assignment envelopes for each stratum. Random assignment envelopes were prepared by the hospital clinical trials unit
Blinding (performance bias and detection bias) All outcomes	Low risk	The following staff were blinded to group assignment: obstetricians who provided clinical care to subjects; nurses who measured maternal body weight and blood pressure, collected and processed maternal blood samples, and analysed urinalyses; labour and delivery room nurses who obtained birthweight; laboratory staff who analysed maternal blood; and staff who performed data entry. Staff who performed maternal body composition analysis, 24-h dietary recalls, and infant anthropometric measurements “were predominantly, but not always”, blinded due to logistical considerations. Formal blinding of subjects was not possible, although subjects were not informed of their group assignments
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	46 women were randomised and infant outcomes were available for 45. There was some loss to follow-up among women with outcome data at 36 weeks available for 38. Reasons for loss were explained and loss was reasonably balanced across groups. It was stated that analysis was by randomisation group irrespective of whether or not women received the intended intervention
Selective reporting (reporting bias)	Unclear risk	Assessment from published study report.
Other bias	Low risk	Baseline characteristics of subjects did not differ between intervention groups

Methods	Randomised clinical trial, set in a referral centre prenatal clinic in Porto Alegre, Brazil, during the period 2000-2002
Participants	Inclusion criteria: healthy, nonsmoking pregnant women, aged 20 years or more, of gestational age less than 20 weeks, having a BMI between 26 and 31 kg/m² (corresponding to a prepregnancy BMI of 25-30 kg/m²) (overweight), and without diabetes or hypertension Exclusion criteria: not stated.
Interventions	Intervention (n = 37): the intervention consisted of a program of supervised physical exercise of 60 minutes duration, performed 3 times per week for 12 weeks. Each session consisted of 5-10 minutes of warm up, 30 minutes of heart rate-monitored aerobic activity, 10-15 minutes of exercise involving upper and lower limbs, and 10 minutes of stretching and relaxation. Aerobic activities were always performed between 50% and 60% of the maximum predicted heart rate, never exceeding 140 beats per minute. The exercises followed the recommendations concerning physical activity practice during pregnancy according to the American College of Sports Medicine, and the American College of Obstetricians and Gynecologists Control (n = 35): the control group participated in once-weekly sessions that included relaxation (respiratory exercises and light stretching but no aerobic or weight-resistance exercises) and focus group discussions concerning maternity. Control participants were neither encouraged to exercise nor discouraged from exercising
Outcomes	Weight gain, low birthweight, prematurity. Weight gain was calculated from different between weight at baseline and weight after 12 weeks of intervention
Notes	At baseline; age (exercise, control) 26.0 ± 3.4, 28.6 ± 5.9 years BMI (exercise, control) 28.0 ± 2.1, 27.5 ± 2.1 kg/m². Gestational age (exercise, control) 17.5 ± 3.3, 18.4 ± 3.9 weeks
*Risk of bias*
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Women were randomised following a blocked sequence generated from a random number table by a statistician not participating in other aspects of the study
Allocation concealment (selection bias)	Low risk	The study coordinator implemented the randomisation by using numbered, opaque envelopes
Blinding (performance bias and detection bias) All outcomes	Low risk	The intervention consisted ofan unblinded program of supervised physical exercise The same cardiologist, blinded to treatment allocation, performed both tests The anaerobic threshold was determined by review of the gas exchange curves by 2 cardiologists working independently and blinded to treatment allocation
Incomplete outcome data (attrition bias) All outcomes	High risk	Loss to follow-up 22%, 19.6%, and 23.9% in intervention and control groups.
Selective reporting (reporting bias)	Unclear risk	Could not determine.
Other bias	High risk	Women in the intervention group were somewhat younger, had higher physical activity, and were earlier in their pregnancy

Methods	Randomised controlled trial, set in private practice of 1 of the physicians, Los Angeles, California
Participants	Pregnant women who were either overweight or gaining weight at an excessive rate. Patients from upper middle class or high social economic groups. There was no other basis for selection or exclusion of participants Average age 24.8 and 25.0 years.
Interventions	Intervention (n = 37): diethylpropion hydrochloride tablet, 75 mg Control (n = 38): placebo tablet.
Outcomes	Weight change at each stage of gestation.
Notes	Age (intervention, control): 24.8, 25.0 years. Average gestation age started medication (intervention, control): 28, 25 weeks BMI (intervention, control): 21.74, 22.45 kg/m². No standard deviations for continuous outcomes were reported
*Risk of bias*
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Used a table of random numbers to assign the patients to active or placebo tablets
Allocation concealment (selection bias)	Unclear risk	No information provided.
Blinding (performance bias and detection bias) All outcomes	Low risk	Double blind procedure.
Incomplete outcome data (attrition bias) All outcomes	High risk	There was a vastly difference drop-out rate between the 2 groups, 10/38 in the intervention group and 28/37 in the control group
Selective reporting (reporting bias)	Unclear risk	Could not determine.
Other bias	Low risk	The pretreatment characteristics were similar.

Methods	Randomised controlled trial, set in Copenhagen, Denmark.
Participants	Inclusion criteria: pregnant obese women (BMI > 30 kg/m²), nondiabetic non-smoking and Caucasian recruited at 15 ± 3 weeks of gestation. Exclusion criteria: smoking, age < 18 or > 45, multiple pregnancy, or medical complication
Interventions	Intervention (n = 23): restriction of gestational weight gain to 6-7 kg by 10 consultation of 1-hour each with trained dietitian. The women were instructed to eat a healthy diet according to the official Danish dietary recommendations (% fat, protein, CHO, 30, 1520, 50-55%). The energy intake was restricted based on individually estimated energy requirements and estimated energetic cost of fetal growth Control (n = 27): the control group had no consultations with the dietitian and had no restrictions on energy intake or gestational weight gain All participants followed the routine clinical schedule.
Outcomes	Weight gain, weight retention at 4 weeks postpartum, pre-eclampsias, caesarean delivery Weight gain was calculated as difference between self-reported prepregnancy weight and weight just before delivery
Notes	Age (intervention, control) 28 ± 4, 30 ± 5 years. Gestational age (intervention, control) 15 ± 2, 16 ± 3 weeks BMI at inclusion visit (intervention, control) 34.9 ± 4, 34.6 ± 3 kg/m²
*Risk of bias*
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	The computerised randomisation took place after the women had given written informed consent
Allocation concealment (selection bias)	Unclear risk	No information provided.
Blinding (performance bias and detection bias) All outcomes	Low risk	The physicians and midwives were blinded in regard to the treatment assignment, and women were asked not to reveal their allocation
Incomplete outcome data (attrition bias) All outcomes	High risk	Loss to follow-up 24%: 17.8% in intervention group, 28.9% in control group
Selective reporting (reporting bias)	Unclear risk	Could not determine.
Other bias	Low risk	Baseline characteristics were similar.

Study	Reason for exclusion
Breslow 1963	Non-randomised controlled trial.
Campbell 2004	Participants included pregnant and nonpregnant women.
Faucher 2008	It was not clear that women in this study were pregnant (community weight loss intervention)
Gray-Donald 2000	Non-randomised controlled trial.
Hausenblas 2008	Participants included both pregnant and postpartum women.
Ismail 1990	Not a relevant intervention.This study examined the use of cefoxitin (an antibiotic) for the prevention of post-cesarean-section infection
Kinnunen 2007	Non-randomised controlled trial.
Moses 2007	Participants were postpartum women (a follow-up study of Moses 2006).
Olson 2004	Non-randomised controlled trial.
Te Morenga 2011	This study did not include pregnant women.
Walker 1966	Non-randomised controlled trial.
Wisner 2006	Participants were postpartum women.

Methods	Randomised controlled trial.
Participants	Pregnant women of the My Baby My Move (MBMM) program.
Interventions	An antenatal community-based physical activity intervention.
Outcomes	Minutes per week of moderate-intensity physical activity.
Notes

Methods	Quasi-experimental randomised and controlled study.
Participants	110 pregnant women referring to Gonabad’s health centres.
Interventions	Nutrition education program on the recommended weight gain during pregnancy; Application of Health Belief Model
Outcomes	Weight gain during pregnancy.
Notes

Trial name or title	Design of the New Life(style) study: a randomised controlled trial to optimise maternal weight gain during pregnancy
Methods	Randomised controlled trial.
Participants	Location: The Netherlands. The aim is to include 275 participants in the study. Women are eligible for participation when they are: expecting their 1st child; able to read, write, and speak Dutch; within their 1st 14 weeks of pregnancy.
Interventions	Intervention: the New Life(style) intervention program consists of 5 individual counselling modules together with a general information brochure Control: usual care.
Outcomes	Primary outcomes: body weight, BMI, and skinfold thickness. Secondary outcomes: physical activity, nutrition and blood levels of factors that are associated with energy homeostasis
Starting date	February 2005.
Contact information	Ellen Althuizen; e.althuizen@vumc.nl Department of Public and Occupational Health, EMGO-Institute, VU UniversityMedical Center, Amsterdam, The Netherlands
Notes	Only protocol has been published. Ongoing for the full publication

Trial name or title	A pregnancy intervention to reduce postprandial glucose excursions in the primary prevention of paediatric obesity
Methods	Randomised controlled trial.
Participants	Location: Australia. Target number of participants: 1650. Inclusion: healthy pregnant women at 12 to 16 weeks’ gestation who agree to be randomised Exclusion: women with pregestational diabetes; multiple birth; assisted reproduction; special diet or referred to a dietitian for other reasons
Interventions	A conventional healthy diet or a low glycaemic index diet from 12 to 16 weeks’ gestation for the remainder of pregnancy
Outcomes	Primary outcomes: prevalence of large gestational age at birth (more than 90th centile); prevalence of childhood obesity as determined by BMI. Secondary outcomes: prevalence of gestational diabetes; ponderal index; prevalence of small-for-gestational age.
Starting date	01/01/2008.
Contact information	Prof Jennie Brand-Miller; j.brandmiller@mmb.usyd.edu.au Human Nutrition Unit, University of Sydney, NSW 2006 Australia
Notes