Obesity and Pregnancy. Guideline of the German Society of Gynecology and Obstetrics (S3-Level, AWMF Registry No. 015-081, June 2019)

Abstract

Aims Obesity is an increasing problem, even in young women of reproductive age. Obesity has a negative impact on conception, the course of pregnancy, and neonatal outcomes. Caring for obese pregnant women is becoming an increasingly important aspect of standard prenatal care. This guideline aims to improve the care offered to obese pregnant women.

Methods This S3-guideline was compiled following a systemic search for evidence and a structured process to achieve consensus.

Recommendations Evidence-based recommendations for the care of obese pregnant women were developed, which cover such as areas as preconception counselling, identification of risks, special aspects of prenatal care and prenatal diagnostic procedures, intrapartum management, and long-term effects on mother and child.

I  Guideline Information

Guidelines program of the DGGG, OEGGG and SGGG

For information on the guidelines program, please refer to the end of this guideline.

Citation format

Obesity and Pregnancy. Guideline of the German Society of Gynecology and Obstetrics (S3-Level, AWMF Registry No. 015-081, June 2019). Geburtsh Frauenheilk 2021; 81: 279–303

Guideline documents

The complete long version and a planned slide version of this guideline as well as a list of the conflicts of interest of all authors are available in German on the homepage of the AWMF: http://www.awmf.org/leitlinien/detail/ll/015-081.html

Guideline authors

See Tables 1 and 2 .

Table 1  Lead author and/or coordinating lead author.

Author	AWMF professional society
Prof. Dr. Ute Schäfer-Graf	German Society of Gynecology and Obstetrics [Deutsche Gesellschaft für Gynäkologie und Geburtshilfe] (DGGG)
Prof. Dr. Markus Schmidt	Obstetrics and Prenatal Medicine Working Group of the DGGG [AG Geburtshilfe und Pränatalmedizin der DGGG]

Table 2  Contributing guideline authors.

Author Mandate holder	DGGG working group (AG)/ AWMF/non-AWMF professional society/ organization/association
Prof. Dr. Regina Ensenauer	German Society of Pediatrics and Adolescent Medicine [Deutsche Gesellschaft für Kinder- und Jugendmedizin] (DGKJ)
Maria Flothkötter	Starting Life Healthy Network (German Federal Ministry of Food and Agriculture) [Netzwerk Gesund ins Leben (Bundesministerium Ernährung und Landwirtschaft)]
Prof. Dr. Ulrich Gembruch	German Society for Prenatal and Obstetric Medicine [Deutsche Gesellschaft für Pränatal- und Geburtsmedizin] (DGPGM)
PD Dr. Tanja Groten	German Society for Perinatal Medicine [Deutsche Gesellschaft für Perinatale Medizin] (DGPM)
Julia Hennike	German Midwifery Society [Deutsche Gesellschaft für Hebammenwissenschaft] (DGHWi)
Prof. Dr. Josef Köhrle	German Society for Endocrinology [Deutsche Gesellschaft für Endokrinologie] (DGE)
Prof. Dr. Maritta Kühnert	Working Group of the Association of German Midwifery Teachers of the DGGG [AG Vereinigung Deutscher Hebammenlehrer der DGGG] (AGVDH)
Jantke Möhler	German Midwives Association [Deutscher Hebammenverband] (DHV)
Annett Schmittendorf	German Midwives Association [Deutscher Hebammenverband] (DHV)
Prof. Dr. Christine Stroh	Surgical Working Group for Obesity Therapy and Metabolic Surgery of the DGAV [Chirurgische Arbeitsgemeinschaft Adipositastherapie und metabolische Chirurgie der DGAV] (CAADIP)
Prof. Dr. Alfred Wirth	German Association for the Study of Obesity [Deutsche Adipositas-Gesellschaft] (DAG)

This guideline was moderated by Dr. med. Monika Nothacker (AWMF-certified guideline moderator).

II  Guideline Application

Purpose and objectives

The guideline aims to create an evidence-based list of recommendations which can be used to improve the care of obese pregnant women.

Targeted areas of patient care

The aim of this guideline is to provide an overview of all areas relevant for prenatal care, starting with preconception counselling. This includes epidemiology, preconception counselling (subcategories: lifestyle, folic acid supplementation, testing for diabetes, adjusting medication), special areas of prenatal care and screening (subcategories: preeclampsia, folic acid and vitamin D supplementation, thrombosis prevention, gestational diabetes, problems of prenatal diagnostic workups, fetal monitoring, prevention of preterm birth, weight gain during pregnancy, bariatric surgery), evaluating risks, effects of lifestyle interventions, planning the birth (subcategories: place of birth, mode of delivery, risks, induction of labor, anesthesia, antepartum breastfeeding advice), birth (subcategories: induced labor, intrapartum monitoring, caesarean section, prevention of uterine atony), neonatal care, and postpartum effects on mother and child.

Target user groups/target audience

The recommendations of this guideline are aimed at the following groups of people:

• registered gynecologists

• gynecologists working in hospitals

• midwives

and provides information to:

• internists and general practitioners, especially those specializing in diabetology

• neonatologists

Other target users (who can use the guideline for information):

• nursing staff

Adoption and period of validity

The validity of this guideline was confirmed by the executive boards/heads of the participating medical professional societies, working groups, organizations and associations as well as by the board of the DGGG and the DGGG guidelines commission in September 2019 and was thus approved in its entirety. This guideline is valid from 1st October 2019 through to 30th September 2024. Because of the contents of this guideline, this period of validity is only an estimate.

III  Methodology

Basic principles

The method used to prepare this guideline was determined by the class to which this guideline was assigned. The AWMF Guidance Manual (version 1.0) has set out the respective rules and requirements for different classes of guidelines. Guidelines are differentiated into lowest (S1), intermediate (S2), and highest (S3) class. The lowest class is defined as consisting of a set of recommendations for action compiled by a non-representative group of experts. In 2004, the S2 class was divided into two subclasses: a systematic evidence-based subclass (S2e) and a structural consensus-based subclass (S2k). The highest S3 class combines both approaches.

This guideline has been classified as: S3

Grading of evidence

Grading of evidence based on SIGN

To assess the level of evidence (level 1 – 4) of studies, this guideline used the classification system of the Scottish Intercollegiate Guidelines Network (SIGN) in its most recent version from 2011 ( Table 3 ).

Table 3  Levels of evidence according to SIGN (November 2011).

Level	Description
Source: http://www.sign.ac.uk/pdf/sign50.pdf
1++	High-quality meta-analyses, systematic review of RCTs, or RCTs with a very low risk of bias
1+	Well-conducted meta-analyses, systematic reviews, or RCTs with a low risk of bias
1−	Meta-analyses, systematic reviews, or RCTs with a high risk of bias
2++	High-quality systematic reviews of case-control or cohort studies, or high-quality case-control or cohort studies with a very low risk of confounding or bias and a high probability that the relationship is causal
2+	Well-conducted case-control studies or cohort studies with a low risk of confounding or bias and a moderate probability that the relationship is causal
2−	Case-control studies or cohort studies with a high risk of confounding or bias and a significant risk that the relationship is not causal
3	Non-analytical studies, e.g., case reports, case series
4	Expert opinion

Grading of recommendations

The grading of evidence in an S3-guideline using a level-of-evidence system also allows the strength of the recommendations made in the guideline to be graded. The degree of recommendation is differentiated into three levels, and the different strengths of recommendation are indicated by the respective semantic choice of words. This commonly used grading of recommendations is not just used by the AWMF but also by the German Medical Association in its National Guidelines on Care ( Nationale Versorgungsleitlinien , NVL). The wording chosen to indicate the strength of the recommendation should be explained in the background text.

In this context, the terms “grade”ʼ, “level” and “strength” indicate the degree of certainty about issuing a recommendation after weighing up the benefits and the harm but are not an indication of whether the recommendation itself is binding. Guidelines are recommendatory, i.e., non-binding.

Individual Statements and Recommendations are differentiated by symbols ( Table 4 ):

Table 4  Level of recommendation (according to Lomotan et al. Qual Saf Health Care 2010).

Symbol	Description	Syntax
A	strong recommendation	must/must not
B	simple recommendation	should/should not
0	open recommendation, not very authoritative	may/may not

Achieving consensus and level of consensus

Authorized participants attended structured NIH-type consensus conferences (S2k/S3-level) during which they voted on preformulated statements and recommendations. Conferences were structured as follows: a recommendation was presented; participants could ask about the contents of the recommendation; proposed amendments were put forward; all proposed amendments were voted on. If a consensus (> 75% of votes) could not be reached, there were more discussions, followed by a final vote. At the end of the session, the strength of the consensus was determined based on the number of persons who participated in the session ( Table 5 ).

Table 5  Strength of consensus based on the level of consensus.

Symbol	Level of consensus	Extent of agreement in percent
+++	Strong consensus	> 95% of participants agree
++	Consensus	> 75 – 95% of participants agree
+	Majority agreement	> 50 – 75% of participants agree
–	No consensus	< 51% of participants agree

Expert consensus

As the name already implies, this refers to consensus decisions taken specifically with regard to recommendations/statements made without a prior systematic search of the literature (S2k) or where evidence is lacking (S2e/S3). The term “expert consensus” (EC) used here is synonymous with terminology used in other guidelines such as “good clinical practice” (GCP) or “clinical consensus point” (CCP). The strength of the recommendation is graded as previously described in the chapter on the grading of recommendations; it is only expressed semantically (“must”/“must not” or “should”/“should not” or “may”/“may not”) without the use of symbols.

IV  Guideline

1  Introduction

1.1  Purpose, target audience

The guideline aims to improve and standardize prevention strategies and prenatal, intrapartum and postpartum care with due consideration given to the particular risks which overweight and obese pregnant women face, using evidence-based recommendations for both outpatient and inpatient settings. The target audience of the guideline consists of gynecologists and obstetricians, internists, general practitioners, endocrinologists and diabetologists, midwives, and neonatologists and should provide information to other groups involved in the care of overweight and obese women, such as nutritionists, psychologists and other professional groups involved in providing healthcare to pregnant women. A list of patient recommendations based on the full-text version must be available to serve as a source of information to pregnant women.

1.2  Definition and epidemiology

Obesity is defined as an increase of body fat which goes beyond normal levels. Body mass index (BMI) serves as the calculation basis for weight classifications. BMI is the quotient of weight divided by the square of the personʼs height (kg/m ² ). The following information on BMI refers to BMI prior to pregnancy. The last survey by the Robert Koch Institute (DEGS1) reported that the obesity rate of women aged 18 – 29 years was 9.6%, the rate for women aged 30 – 39 years was 17.9% and the rate for women aged 40 – 49 years was 18.6%. The data from the 2017 Perinatal Survey show an obesity rate of 14.69% for pregnant women in Germany ( Table 6 ).

Table 6  Prevalence of overweight or obesity in pregnant German women, according to a 2017 prenatal survey.

	2017		2016
	n	%	n	%
Total number of pregnant women	n = 761 176		n = 758 614
BMI at the first examination
< 20	92 510	12.15	94 199	12.42
20 – < 25	339 435	44.59	342 377	45.13
25 – < 30	167 015	21.94	164 154	21.64
≥ 30	111 840	14.69	107 499	14.17
Data could not be utilized	50 376	6.62	50 385	6.64

2  Preconception counselling

2.1  Preconception lifestyle interventions

The existing studies suggest that a lifestyle with increased levels of exercise and proper nutrition prior to conception can have positive effects both on pregnancy and on delivery/birth and the postpartum period.

2.2  Folic acid supplementation

Obese women have a higher risk of giving birth to children with neural tube defects. There are no intervention studies which provide evidence on the preventive effect of higher doses of folic acid in obese women on the rate of neural tube defects in their children. This guideline therefore does not support supplementing 5 mg folic acid/day in obese women before and during pregnancy as recommended in the Irish and English guidelines.

2.3  Adjusting medication

Obesity is often accompanied by chronic comorbidities, which must be investigated prior to becoming pregnant. Typical comorbidities include hypertension, hyperlipidemia, diabetes mellitus, and polycystic ovary (PCO) syndrome.

2.4  Counselling after obesity-related and metabolism-related surgical procedures

Pregnancy should be avoided in the period immediately after obesity surgery and metabolic surgery and should also be avoided during the weight loss stage in the first 12 months after surgery, as the pregnant woman and her fetus could be at risk of nutritional deficiencies during the weight loss stage.

The issue of what constitutes the most suitable form of contraception is particularly relevant following malabsorption procedures; there are no studies on resorption and oral contraceptives. The use of oral contraceptives after the above-listed surgical procedures is not reliable and patients should be advised to use other methods of contraception. The treating gynecologist must provide counselling about (reliable) methods of contraception.

2.5  Investigation of comorbidities

Overweight and obesity are often associated with comorbidities. Particularly if women want to have children, these comorbidities must be investigated and suitably treated before the women become pregnant. This particularly applies to diabetes. The number of cases with type 2 diabetes only detected in pregnancy in the context of screening for gestational diabetes is rising. The appropriate approach which should be used to diagnose diabetes has been described in the Practice Recommendations of the German Diabetes Society.

Polycystic ovary syndrome (PCOS) and its typical association with insulin resistance is common in obese women; women wanting to have children are treated with metformin. The DGGG has issued a detailed position paper on the appropriate approach for women with PCOS receiving metformin who become pregnant.

Hypertension is another comorbidity typically associated with obesity. Prior to conception, obese women with hypertension should be primarily switched to methyldopa or β-blockers or nifedipine.

3  Special aspects of prenatal care

3.1  Obesity and preeclampsia

Obesity is an important risk factor for preeclampsia; a BMI of ≥ 30 kg/m ² increases the risk of preeclampsia by a factor of 3 – 5.

3.2  Vitamin D substitution

Fetal access to vitamin D, calcium and phosphate is determined by maternal status and placental function. Up to 25% of pregnant women are vitamin D deficient. The currently available recommendations on vitamin D supplementation during pregnancy are controversial; there has been no differentiation of proposed doses based on BMI.

The findings reported in studies on the impact of maternal 25-OH D levels on the bone mass of their children have been inconsistent. However, the majority of studies have confirmed an association between vitamin D deficiency and lower peak bone mass in children. Meta-analyses and reviews of observational studies point to the fact that inadequate vitamin D intake (< 30 ng/dl) is associated with a higher risk of preterm birth (PTB) and small-for-gestational-age (SGA) fetuses, depending on the vitamin D concentration and the week of gestation. There is no association with the prevalence of gestational diabetes mellitus (GDM).

3.3 Thrombosis prevention

Obesity is a risk factor for venous thromboembolism in pregnancy. Even without the presence of additional risk factors such as prior history of thrombosis or thrombophilia, obese women should be categorized as “at moderate risk”. The risk of venous thromboembolism (VTE) is already higher in the first trimester of pregnancy and remains high in all trimesters of pregnancy. The highest risk is in the first postnatal week due to the vascular damage which occurs during the birth.

3.4  Diagnosing GDM

Overweight pregnant women are at increased risk of developing gestational diabetes. The risk increases with increasing BMI, irrespective of other risk factors such as age, weight gain in pregnancy, socioeconomic status, parity, and pre-existing or pregnancy-induced hypertension, and is highest in extremely obese Hispanic population groups (RR 3.4). Because of the high risk of glucose metabolism disorders and the increasing prevalence of type 2 diabetes in young women, investigating GDM is already recommended in the 1st trimester of pregnancy. For information on screening and diagnostic procedures for high-risk groups, including in early pregnancy, cf. AWMF 057/008.

3.5  Efficiency of prenatal diagnostic workup

Maternal obesity and the extent of maternal obesity is a decisive factor which affects the quality of ultrasound examinations and prenatal diagnostic and monitoring procedures.

Increased frequency of fetal anomalies associated with maternal obesity

Chromosomal aberrations are not more common with maternal obesity. However, the increased incidence of non-chromosomal fetal malformations associated with obese and, to a limited extent, even with overweight pregnant women is highly relevant for prenatal diagnostic procedures. This particularly includes cardiac malformations and neural tube defects. Their frequency of occurrence correlates with the extent of maternal obesity and maternal BMI. The pathophysiological mechanism responsible for the rise in non-chromosomal malformations associated with an increasing BMI in overweight and obese women is not clear. Potential causes currently being debated include maternal hyperinsulinism and relative folic acid deficiency.

However, in contrast to pregnant women with pre-existing diabetes mellitus, increasing the folate intake in obese pregnant women who took at least 400 µg folic acid every day resulted in no or only a very marginal decrease in the frequency of neural tube defects.

Physical limitations of ultrasound because of maternal obesity

Maternal BMI correlates with abdominal adipose tissue and is therefore directly linked to a reduction in imaging quality and visibility during transabdominal ultrasound. The poorer image quality makes it much more difficult to carry out useful ultrasound examinations in every trimester of pregnancy. This particularly applies to fetal echocardiography, where the quality of the two-dimensional image is not only poorer but even the quality of the color Doppler image is poorer because of the lower signal intensity.

In the first trimester, ultrasound measurement of fetal crown-rump length and/or biparietal diameter is used to check the calculated gestational age of the fetus. This is particularly important for obese women because they are more likely to have menstruation disorders. Successful imaging and the required measurement of nuchal translucency becomes increasingly difficult or even impossible as the thickness of the abdominal wall increases, and imaging requires more time.

In the second trimester (18 – 22 weeks of gestation), it becomes ever more difficult to obtain complete imaging of organs as the BMI and the size of the abdominal pannus increases. Detection rates for fetal malformations based on ultrasound examinations done in the second trimester decrease significantly as maternal BMI in the second trimester increases and are up to 20% lower in the overall group of obese pregnant women (BMI ≥ 30 kg/m ² ) compared to normal-weight pregnant women. At the genetic ultrasound examination, the imaging quality of relevant soft markers such as nuchal fold thickness > 5 mm, echogenic papillary muscle, echogenic intestines, renal pyelectasis, nasal bone, and pre-nasal skin thickness is 20 to 50% lower, depending on the extent of obesity, so that genetic sonography is not recommended for severely obese pregnant women with a high initial risk.

Ultrasound examinations done in the third trimester are largely performed to monitor fetal growth and status. Some studies have reported that the precision of weight estimation is lower in obese pregnant women, depending on the extent of obesity [93]; however, several recent studies have not confirmed this. In principle, sonography-based weight estimation in obese pregnant women should be done by experienced examiners.

Even invasive prenatal diagnostic procedures (chorionic villous sampling, amniocentesis and fetal blood sampling) and fetal therapeutic interventions are more difficult and often require several attempts and repeat punctures.

Biochemical analysis

The concentrations of biochemical markers used to screen for aneuploidy, neural tube defects and disorders of placentation (preeclampsia, IUGR) such as PAPP-A, PlGF, β-hCG, AFP, uE3 and inhibin decrease significantly as maternal weight increases; the same applies to pregnant women with diabetes mellitus.

The diagnostic certainty of cell-free DNA analysis (cfDNA screening, cfDNA testing) of maternal blood (non-invasive prenatal testing [NIPT]) based on the cell-free fetal DNA (cffDNA) circulating in maternal blood is limited in cases with severe maternal obesity. As maternal weight increases, the percentage of cffDNA in serum continually decreases. The average percentage of cffDNA in the maternal bloodstream of a mother weighing 60 kg is 11.7%; the average percentage in a mother weighing 160 kg is 3.9%.

3.6  Measures to avoid preterm birth

According to studies, obese pregnant women have a significantly higher risk of spontaneous abortion after natural conception. The risk of miscarriage and preterm birth also increases in pregnant women with excessive weight gain. A review of two cohort studies carried out in Sweden and the USA by Gould et al. showed an increased risk of extreme preterm birth between the 22nd and 27th week of gestation, particularly in the group of women with severe obesity and a BMI > 40 kg/m ² . There are few prospective studies on serial measurement of cervical length, progesterone supplementation or other prophylactic measures in obese pregnant women compared to normal-weight pregnant women.

3.7  Antepartum monitoring

Obese pregnant women in the last trimester of pregnancy require intensified fetal monitoring adapted to the particular risks associated with obesity. The risk of gestational diabetes is 3 times higher compared to normal-weight pregnant women; the risk of preeclampsia doubles with every increase of 5 kg/m ² in maternal BMI, and a meta-analysis showed an increased risk of intrauterine and neonatal death in overweight and obese pregnant women [108]. Depending on the study, the risk of intrauterine fetal death (IUFD) close to term (in weeks 37 – 40 of gestation) is 1.7 – 3.5 times higher in obese pregnant women, with an OR of 4.6 (1.6 – 13.5) for > 40 weeks of gestation [108, 111]. It has been suggested that there is a connection between this higher risk of fetal death and the increased risk of (late) intrauterine growth retardation, which is known to be higher for the fetuses of obese pregnant women. Carrying out another fetal biometric examination after the 3rd screening is essential to prevent stillbirths close to term for missed IUGR and also to detect cases of macrosomia which will have implications for planning the birth.

3.8  Weight gain in pregnancy

Excessive weight gain higher than that recommended by the Institute of Medicine (IOM) has been observed in 37 – 50% of pregnant women with a BMI > 25 kg/m ² .

Excessive weight gain above the range recommended by the IOM is associated with a higher birth weight and/or a birth weight > 90th percentile (LGA) and a higher neonatal fat percentage. Studies which recorded separate data for pregnant women with a BMI ≥ 30 kg/m ² reported a significantly higher birthweight, z-score and LGA rate for this group.

The data on the birth weight of neonates born to women whose weight gain was below the range recommended by the IOM are inconsistent; it is thought that it could impair fetal growth. These concerns have not been confirmed in the majority of studies. However, the LGA rate was found to be significantly lower. The authors concluded that maternal weight gain below the range recommended by the IOM leads to better outcomes for obese pregnant women and that the IOM recommendations should be modified accordingly.

Data about the impact on GDM or the prevalence of preeclampsia are inconsistent but, generally, it appears that the impact of reducing weight gain is too low to affect the outcome.

The data from studies on the connection between excessive weight gain and long-term child outcomes is controversial because a significant effect was only observed in three of the seven cited studies.

3.9  Pregnancy after obesity surgery and metabolic surgery

Compared with obese pregnant women, pregnancy after obesity surgery and metabolic surgery is associated with a lower risk of gestational diabetes and fetal macrosomia; on the other hand, there is a higher risk of intrauterine growth restriction. The risk of stillbirth or perinatal death does not differ significantly although there is tendency for it to be slightly higher (1.7 vs. 0.7%; OR 2.39; 95% CI: 0.98 – 5.85; p = 0.06).

Because of the dumping effect, oral glucose tolerance tests (oGTTs) must not be used to investigate patients who have had combined or malabsorptive procedures (e.g., gastric bypass, omega loop gastric bypass, biliopancreatic diversion with duodenal switch) for gestational diabetes.

4  Lifestyle interventions in pregnancy

There are numerous studies on weight gain, maternal risks and child outcomes following lifestyle changes. Some of these studies were carried out exclusively in overweight/obese pregnant women. The aim was to comply with the recommendations of the IOM. A meta-analysis of 36 RCT studies showed that a change in diet, increased exercise, or a combination of both reduces the weight gain of overweight or obese pregnant women by 0.75 kg and 0.73 kg.

A meta-analysis of 4 studies on nutrition and 10 studies on physical activity showed a decrease in gestational diabetes of 21 and 34%, respectively.

The majority of studies on the development of hypertension reported that physical activity exerted a significant protective effect. Whether lifestyle changes have an impact on the duration of pregnancy or preterm birth cannot be currently determined.

5  Planning the birth

5.1  Induction of labor

In the absence of other obstetric or medical indications, obesity alone is not an indication to induce labor. The respective currently valid obstetrical recommendations apply. Obese patients have a higher risk of requiring induction of labor due to higher rates for complications of pregnancy [159]. However, in many cases attempts to induce labor are unsuccessful. In the AWMF guideline on the approach for post-term pregnancies, the risk of IUFD irrespective of whether the pregnancy was post-term or not was reported to be higher in women with a BMI ≥ 30 kg/m ² by a factor of 1.6, and the guideline states that pregnant women must be informed about this when they are being advised about inducing labor. The existing literature does not provide information on whether inducing labor in obese pregnant women offers the best chances of success and, if so, which method is most suitable. A recent meta-analysis of 8 studies came to the overall conclusion that obesity is associated with higher doses of prostaglandins and oxytocin. There are no BMI-specific data on the efficacy of using balloons to induce labor. It is conceivable that the response could be better than with prostaglandins as there are no issues about adjusting dosages according to the level of obesity.

5.2  Choosing the place to give birth

Obese pregnant women are classified as higher risk, meaning that choosing an appropriate place to give birth is necessary. Several meta-analyses have established that the neonatal mortality risk is significantly higher for women with a BMI ≥ 30 and that the neonatal mortality risk increases in proportion to the increase in maternal BMI.

Causes include a higher incidence of preterm birth, maternal comorbidities, and intrapartum complications.

Obese pregnant women have lower success rates for spontaneous delivery if they have previously given birth by caesarean section. However, there is no evidence that prior caesarean section is an indication for primary repeat caesarean section.

5.3  Anesthetic options

Pregnant women with a BMI > 40 kg/m ² must have a prenatal consultation with an anesthesiologist with obstetric experience to identify potential anesthesia-related problems. Ideally, an anesthesia treatment plan would be developed during the consultation which would then feed into the pregnant womanʼs subsequent obstetric care. The analgesic obstetric options must also be determined and discussed during the consultation.

5.4  Determining the mode of delivery

There is no new literature or any studies which have explicitly investigated this issue. There are no prospective studies comparing outcomes after primary caesarean section or spontaneous delivery in obese patients who have previously given birth by caesarean section or even the results for primiparous women. The existing international guidelines ultimately state that the decision for or against vaginal delivery must be made based on the individual factors affecting the specific woman.

Obese women have lower success rates for spontaneous delivery if they have previously given birth by caesarean section. Durnwald and other authors have reported a success rate of just 13% for vaginal delivery after prior caesarean section in women weighing > 136 kg.

In the absence of contraindications, a pregnant woman who has previously given birth by caesarean section may be offered the option to attempt a vaginal birth. In principle, this also applies to obese pregnant women.

5.5  Intrapartum monitoring

There may be some technical problems when obese pregnant women give birth. For women with a BMI > 40 kg/m ² it is advisable to place an epidural catheter in the early stages of labor in preparation for the later administration of an anesthetic/analgesia during childbirth or a possible secondary caesarean section. The anesthesiologist should be informed as soon as a pregnant woman with a BMI ≥ 40 kg/m ² is brought to the delivery room.

5.6  Caesarean section approach

Although obese pregnant women do not have a higher intraoperative risk during caesarean sections compared to normal-weight women, obese women are at higher risk postoperatively; in particular, they have a higher risk of disturbances of wound healing.

Placement of the abdominal incision depends on the patientʼs physical characteristics (distribution of adipose tissue, etc.). There are no data indicating whether a transverse or a longitudinal incision is preferable. A sufficiently large incision is particularly important when delivering a large neonate. A low transverse uterine incision with suturing of the subcutis if it is thicker than 2 cm should be done in women with a BMI of ≥ 35 kg/m ² . A Cochrane analysis of 7 studies showed that suturing the subcutis reduces the risk of hematomas, seromas, infections and wound dehiscence, although the studies did not differentiate between different thicknesses of subcutaneous adipose tissue. When a supraumbilical approach was chosen, there was a higher risk of perioperative maternal blood loss of > 1000 ml; however, there was no significant difference in the rate of wound healing complications.

6  Postpartum aspects

6.1  Breastfeeding support

The existing evidence on the rate of breastfeeding among obese women is limited. Women who were obese prior to conception are less likely to start breastfeeding compared to normal-weight women and the period in which they breastfeed is shorter.

Evidence-based Recommendation 2.E1.

Level of evidence 1+

Level of recommendation B

Level of consensus +++

Obese women wanting to have children should be encouraged to participate in a lifestyle intervention prior to conception.

Evidence-based Recommendation 2.E2.

Level of evidence 1+

Level of recommendation A

Level of consensus +++

Obese women who are planning to become pregnant must take a folic acid supplement amounting to 400 µg folic acid/day which is the same as that recommended to all other women planning to become pregnant in addition to having a folate-rich/balanced diet.

Consensus-based Recommendation 2.E3.

Expert consensus

Level of recommendation B

Level of consensus +

After bariatric surgery, women wanting to become pregnant should take a supplement of 800 µg folic acid.

Evidence-based Recommendation 2.E4.

Level of evidence 1+

Level of recommendation A

Level of consensus +++

Women must start taking folic acid supplements at least four weeks prior to conception and must continue to take them until the end of the first trimester of pregnancy.

Evidence-based Recommendation 2.E5.

Level of evidence 4

Level of recommendation A

Level of consensus +

Obese women must already be specifically advised about supplementation with folic acid in the phase when they are planning to become pregnant and in early pregnancy.

Consensus-based Recommendation 2.E6.

Expert consensus

Level of recommendation B

Level of consensus +++

Existing medication must be reviewed by an interdisciplinary group prior to starting pregnancy and adjusted where necessary.

Evidence-based Recommendation 2.E7.

Level of evidence 4

Level of recommendation B

Level of consensus +++

Patients of childbearing age who have undergone obesity surgery or metabolic surgery must use a reliable method of contraception during the weight loss stage.

Evidence-based Recommendation 2.E8.

Level of evidence 2++

Level of recommendation A

Level of consensus +++

Existing and potential comorbidities should be investigated and appropriately treated prior to conception.

Evidence-based Recommendation 3.E9.

Level of evidence 2+

Level of recommendation B

Level of consensus ++

Overweight pregnant women with a BMI of more than 25 kg/m ² should be offered an individual risk calculation for preeclampsia between weeks 11 + 0 and 13 + 6 of gestation.

Evidence-based Recommendation 3.E10.

Level of evidence 1+

Level of recommendation B

Level of consensus ++

Women with an individually calculated risk of preeclampsia of > 1 : 100 should take acetylsalicylic acid 150 mg/day to reduce the rate of preeclampsia before the 37th week of gestation.

Evidence-based Recommendation 3.E11.

Level of evidence 4

Level of recommendation B

Level of consensus ++

Women with a BMI of > 35 kg/m ² should take acetylsalicylic acid 150 mg/day from week 11 + 0 of gestation.

Evidence-based Recommendation 3.E12.

Level of evidence 3

Level of recommendation 0

Level of consensus +++

In specific cases, vitamin D supplements may be indicated for pregnant women who are unable to or have a reduced ability to self-synthesize vitamin D. Recommendations range from 200 to 600 UL/day. There are no dosage recommendations for obese women.

Evidence-based Recommendation 3.E13.

Level of evidence 2+

Level of recommendation B

Level of consensus ++

In addition to nonpharmacologic prophylaxis of VTE, overweight pregnant women with two or more additional risk factors should receive pharmacological VTE prophylaxis for as long as they are at increased risk and in the period following childbirth (up to 6 weeks post partum).

Evidence-based Recommendation 3.E14.

Level of evidence 2+

Level of recommendation B

Level of consensus +++

Overweight women who did not receive pharmacological prophylaxis ante partum but were delivered by caesarean section and/or have a positive familial history for VTE or an additional risk factor should receive pharmacological VTE prophylaxis post partum in addition to physical prophylactic measures.

Evidence-based Recommendation 3.E15.

Level of evidence 2++

Level of recommendation A

Level of consensus +++

Overweight women are at higher risk for gestational diabetes and undetected type 2 diabetes and must therefore already be advised to test for glucose metabolism disorders in the first trimester of pregnancy.

Evidence-based Recommendation 3.E16.

Level of evidence 2++

Level of recommendation A

Level of consensus +++

If the transabdominal ultrasound examination performed in the first trimester of pregnancy in weeks 12 – 14 of gestation is incomplete, an attempt must be made to complete the examination by carrying out a transvaginal examination.

Evidence-based Recommendation 3.E17.

Level of evidence 2++

Level of recommendation A

Level of consensus +++

If the transabdominal ultrasound examination done in the first trimester of pregnancy in weeks 12 – 14 of gestation is incomplete, a repeat examination must be carried out very soon afterwards (within 1 – 2 weeks). Depending on the respective initial situation, a more experienced examiner must be called in and a better-quality ultrasound device must be used. If necessary, this examination must also be carried out as a transvaginal examination.

Evidence-based Recommendation 3.E18.

Level of evidence 2++

Level of recommendation A

Level of consensus ++

When biochemical procedures (PAPP-A, free β-HCG, AFP, PlGF, etc.) are used to calculate risk, the results must be adjusted according to maternal weight.

Evidence-based Recommendation 3.E19.

Level of evidence 2++

Level of recommendation A

Level of consensus +++

If the percentage of cell-free fetal DNA (cffDNA) remains too low for assessment despite repeated taking of blood samples, the pregnant woman must be advised to have an invasive diagnostic workup; alternately, she must obtain a detailed differential diagnosis based on a detailed sonographic workup in weeks 12 – 14 of gestation, as the risk of trisomy 13, trisomy 18 and triploidy is higher in this group of women.

Evidence-based Recommendation 3.E20.

Level of evidence 2+

Level of recommendation A

Level of consensus +++

The pregnant woman must be informed about the limited informative value of the respective ultrasound examinations and also be informed that ultrasound examinations will take longer and repeat examinations are necessary.

Evidence-based Recommendation 3.E21.

Level of evidence 2+

Level of recommendation A

Level of consensus +++

If the ultrasound examination performed in the second trimester of pregnancy in week 18 + 0 – 21 + 6 of gestation is incomplete, then a repeat examination must be carried out at short notice in week 22 + 0 – 23 + 6 of gestation. Depending on the respective initial situation, a more experienced examiner must be called in and a better-quality ultrasound device must be used.

Evidence-based Recommendation 3.E22.

Level of evidence 4

Level of recommendation B

Level of consensus ++

In view of the higher risk of obese pregnant women, particularly of nulliparous obese pregnant women, of developing hypertensive disorders of pregnancy (gestational hypertension and preeclampsia) and the higher risk of fetal growth restriction due to maternal uteroplacental dysfunction, Doppler sonography to investigate both uterine arteries should be offered in week 20 – 24 of gestation to assess the risk.

Evidence-based Recommendation 3.E23.

Level of evidence 4

Level of recommendation A

Level of consensus ++

If an examination is not completed or fetal structures and organs cannot be adequately visualized, this must be recorded and communicated to the pregnant woman.

Evidence-based Recommendation 3.E24.

Level of evidence 2−

Level of recommendation C

Level of consensus ++

Fetal magnetic resonance imaging may be indicated in specific cases after all other ultrasound options have been exhausted.

Evidence-based Recommendation 3.E25.

Level of evidence 3

Level of recommendation B

Level of consensus +++

Particular attention must be paid to any risk factors for preterm birth when providing obese pregnant women with prenatal care.

Evidence-based Recommendation 3.E26.

Level of evidence 4

Level of recommendation B

Level of consensus +++

Because of the increased risk of maternal and fetal complications, pregnant women with a BMI > 40 kg/m ² should undergo a weekly examination from week 36 + 0 of gestation.

Evidence-based Recommendation 3.E27.

Level of evidence 4

Level of recommendation A

Level of consensus ++

Intensified antenatal CTG monitoring in obese pregnant women is not indicated because of maternal obesity alone.

Evidence-based Recommendation 3.E28.

Level of evidence 2+

Level of recommendation B

Level of consensus ++

In addition to ultrasound screening in the third trimester (carried out in weeks 28 + 0 – 31 + 6 of gestation in accordance with the German maternity guidelines), a further biometric ultrasound examination should be carried out in obese pregnant women in week 34 – 36 of gestation to detect fetal growth restriction or LGA growth in late pregnancy.

Evidence-based Recommendation 3.E29.

Level of evidence 2+

Level of recommendation A

Level of consensus +++

The recommendations of the IOM on maternal weight gain in pregnancy must not be exceeded.

Evidence-based Recommendation 3.E30.

Level of evidence 2+

Level of recommendation B

Level of consensus ++

A weight gain below the IOM recommendation of 5 – 9 kg should be considered for women with a BMI ≥ 30 kg/m ² .

Evidence-based Recommendation 3.E31.

Level of evidence 4

Level of recommendation B

Level of consensus +++

Patients of childbearing age who have undergone obesity surgery or metabolic surgery should have a reliable form of contraception during the weight loss stage.

Evidence-based Recommendation 3.E32.

Level of evidence 4

Level of recommendation C

Level of consensus +++

The gastric band may be loosened in patients who have undergone gastric banding.

Evidence-based Recommendation 3.E33.

Level of evidence 4

Level of recommendation C

Level of consensus +++

If there are no obstetric contraindications, patients who have had obesity surgery or metabolic surgery may have a spontaneous delivery.

Evidence-based Recommendation 3.E34.

Level of evidence 4

Level of recommendation A

Level of consensus +++

The supplementation doses of patients who have undergone obesity surgery or metabolic surgery must be adapted to the results of laboratory tests at least 1 × in every trimester of pregnancy.

Evidence-based Recommendation 3.E35.

Level of evidence 4

Level of recommendation A

Level of consensus +++

oGTT must not be used in patients who have undergone obesity surgery or metabolic surgery. Instead, patients must be monitored using venous fasting blood glucose levels and 24-hour blood glucose profiles.

Evidence-based Recommendation 3.E36.

Level of evidence 4

Level of recommendation A

Level of consensus +++

Women who become pregnant after obesity surgery or metabolic surgery must not continue to lose weight.

Evidence-based Recommendation 3.E37.

Level of evidence 4

Level of recommendation A

Level of consensus +++

Women who become pregnant after obesity surgery or metabolic surgery must be followed up closely and must have a gynecological examination.

Evidence-based Recommendation 3.E38.

Level of evidence 2+

Level of recommendation A

Level of consensus +++

Because all pregnancies after obesity surgery or metabolic surgery are considered high-risk pregnancies, the growth of the fetus must be closely monitored.

Evidence-based Recommendation 3.E39.

Level of evidence 4

Level of recommendation A

Level of consensus +++

It is important to be aware of the possibility of hernia or volvulus if abdominal symptoms occur during pregnancy or in the postpartum period in women who have had obesity surgery or metabolic surgery.

Evidence-based Recommendation 4.E40.

Level of evidence 1−

Level of recommendation A

Level of consensus +++

Obese pregnant women must be advised to increase their level of exercise, to exercise regularly and to change their diet in accordance with the recommendations of the German Nutrition Society (DGE).

Evidence-based Recommendation 5.E41.

Level of evidence 1+

Level of recommendation B

Level of consensus +++

Pregnant women with a BMI ≥ 30 kg/m ² should be informed that the post-term pregnancies of obese women are at higher risk of intrauterine fetal death (IUFD).

Evidence-based Recommendation 5.E42.

Level of evidence 1+

Level of recommendation B

Level of consensus ++

If additional risk factors are present, obese pregnant women should be offered the option of inducing labor from week 39 + 0 of gestation and the risks should be carefully weighed up.

Evidence-based Recommendation 5.E43.

Level of evidence 4

Level of recommendation B

Level of consensus +++

Medical staff should be trained how to care for obese pregnant women and deal with the obstetric complications of obese women as well as how to use special technical equipment and devices.

Evidence-based Recommendation 5.E44.

Level of evidence 4

Level of recommendation B

Level of consensus +++

Obstetric vaginal surgery and caesarean sections in obese pregnant women should be done by specialized gynecologists and anesthesiologists.

Evidence-based Recommendation 5.E45.

Level of evidence 2++

Level of recommendation B

Level of consensus +++

Pregnant women with a BMI > 35 kg/m ² should give birth in perinatal centers.

Evidence-based Recommendation 5.E46.

Level of evidence 4

Level of recommendation B

Level of consensus +++

Pregnant women with a BMI of between 30 – 35 kg/m ² prior to conception should be provided with an individualized risk assessment concerning the place of birth.

Evidence-based Recommendation 5.E47.

Level of evidence 4

Level of recommendation A

Level of consensus +

Obese pregnant women who have previously given birth by caesarean section must give birth in a perinatal center.

Evidence-based Recommendation 5.E48.

Level of evidence 4

Level of recommendation B

Level of consensus +++

Institutions which provide care to obese pregnant women with a BMI ≥ 30 kg/m ² should have the following:

• sufficient room to move;

• equipment capable of bearing heavy loads (up to 250 kg): wheeled stretchers and examination couches, delivery tables, operating tables, wheelchairs, etc.;

• appropriate medical instruments and devices, e.g., extra-large blood pressure cuffs, extra-long epidural and spinal needles, large specula, etc.;

• staffing ratios adapted to allow for more intensive monitoring;

• suitable surgical gowns.

Evidence-based Recommendation 5.E49.

Level of evidence 4

Level of recommendation B

Level of consensus +++

Medical staff should receive regular training on how to care for obese women and deal with their obstetric complications as well as how to use special devices and equipment.

Evidence-based Recommendation 5.E50.

Level of evidence 3

Level of recommendation A

Level of consensus +++

Pregnant women with a BMI > 40 kg/m ² must have a prenatal consultation with an anesthesiologist with obstetric experience to identify special anesthesia-related problems. An anesthesia treatment plan must be developed during the consultation and implemented as part of the pregnant womanʼs subsequent obstetric care.

Evidence-based Recommendation 5.E51.

Level of evidence 4

Level of recommendation A

Level of consensus +++

Obese pregnant women with comorbidities such as obstructive sleep apnea must consult with an anesthesiologist because they are at higher risk of hypoxemia, hypercapnia and sudden death.

Evidence-based Recommendation 5.E52.

Level of evidence 4

Level of recommendation A

Level of consensus +++

In obese women, an intravenous line must be placed at an early stage during labor.

Evidence-based Recommendation 5.E53.

Level of evidence 4

Level of recommendation 0

Level of consensus +++

If fetal monitoring is sufficient and fetal stress is excluded, longer labor times to delivery may be tolerated in obese women if the aim is a vaginal delivery.

Evidence-based Recommendation 5.E54.

Level of evidence 4

Level of recommendation A

Level of consensus +

Obesity is not an indication for primary caesarean section and must be avoided because of the increased risk of complications.

Evidence-based Recommendation 5.E55.

Level of evidence 4

Level of recommendation A

Level of consensus +++

Obese pregnant women who have previously given birth by caesarean section must be informed about the chances of success and the risks of a vaginal birth as well as about the risks associated with primary and secondary repeat caesarean section. The decision must be made based on their specific individual needs.

Evidence-based Recommendation 5.E56.

Level of evidence 4

Level of recommendation A

Level of consensus ++

If the quality of the results of external fetal heart rate monitoring is inadequate, then a scalp electrode must be placed for internal monitoring.

Evidence-based Recommendation 5.E57.

Level of evidence 4

Level of recommendation A

Level of consensus ++

It is important to ensure that maternal and fetal heart rates can be reliably differentiated during monitoring.

Evidence-based Recommendation 5.E58.

Level of evidence 4

Level of recommendation A

Level of consensus +++

An appropriately sized blood pressure cuff must be used to measure the blood pressure of obese patients.

Evidence-based Recommendation 5.E59.

Level of evidence 4

Level of recommendation A

Level of consensus +++

An intravenous line must be placed in the early stages of labor when caring for moderately to severely obese women.

Evidence-based Recommendation 5.E60.

Level of evidence 4

Level of recommendation A

Level of consensus +++

Staff in the operating room must be informed about the admission of any woman weighing more than 120 kg who will require surgery.

Evidence-based Recommendation 5.E61.

Level of evidence 1++

Level of recommendation B

Level of consensus +

A low transverse uterine incision with suturing of the subcutis if it is thicker than 2 cm should be done in women with a BMI of > 35 kg/m ² .

Evidence-based Recommendation 5.E62.

Level of evidence 1++

Level of recommendation A

Level of consensus ++

A cephalosporin (e.g., cefazoline) must be administered prophylactically 60 min before making the incision: 2 g IV for women weighing < 120 kg, 3 g IV for women weighing > 120 kg. Alternatively, for women allergic to penicillin: clindamycin 900 mg IV combined with gentamicin 5 mg/kg IV.

Evidence-based Recommendation 5.E63.

Level of evidence 1

Level of recommendation A

Level of consensus +++

Subcutaneous drains must not be routinely placed.

Evidence-based Recommendation 5.E64.

Level of evidence 2−

Level of recommendation 0

Level of consensus +

A subumbilical or supraumbilical approach may provide fast access to the uterus but is associated with higher perioperative morbidity rates.

Evidence-based Recommendation 6.E65.

Level of evidence 4

Level of recommendation B

Level of consensus +++

Obese women who have given birth should be given special support to breastfeed.

Evidence-based Recommendation 6.E66.

Level of evidence 2+

Level of recommendation A

Level of consensus +++

Children born to mothers who had a BMI of ≥ 25 kg/m ² before conception must be monitored at the routine infant and child health screening examinations for any unusual developments in their BMI and their guardians must be given advice early on.