Alternative positions for the baby at birth before clamping the umbilical cord

Abstract

Background

The third stage of labour is from birth of the baby until delivery of the placenta. Clamping the umbilical cord is one component of active management of the third stage. Deferring cord clamping allows blood flow between the baby and the placenta to continue; net transfer to the baby is called placental transfusion. If the cord is clamped immediately placental transfusion is restricted. Gravity is one of several factors that may influence the volume and duration of placental transfusion at both vaginal and caesarean births. Hence raising or lowering the baby whilst the cord is intact may influence placental transfusion, which in turn may affect outcome for the baby and the woman.

Objectives

To compare the effects of alternative positions for the baby between birth and cord clamping on outcome for the baby, outcome for the mother and on use of health service resources.

Search methods

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (July 2010).

Selection criteria

Randomised trials comparing alternative positions for the baby at vaginal and caesarean birth, before clamping of the umbilical cord.

Data collection and analysis

We independently assessed trial eligibility and quality. When necessary, we contacted study authors for additional information.

Main results

Thirty‐seven studies (7559 mother‐infant pairs) were excluded: 33 (7296) because they did not compare alternative positions for the baby before clamping the umbilical cord and four (263) due to quasi‐random allocation. No studies met the inclusion criteria. One additional trial is ongoing.

Authors' conclusions

No randomised trials have assessed the influence of gravity on placental transfusion. Large, well‐designed randomised trials are needed to assess whether gravity influences placental transfusion at vaginal and caesarean births and, if so, whether this affects short‐term and long‐term outcome for the baby and for the mother.

Plain language summary

Alternative positions for the baby immediately at birth before clamping the umbilical cord

There is no reliable research to show whether lifting or lowering the baby in the time between birth and cord clamping makes a difference to the health of the baby or the mother. If the cord is not clamped immediately at birth, blood will usually continue to flow between the placenta and the baby for a few minutes. The net blood volume transferred to the baby during this time is called 'placental transfusion'. The amount of blood and how long it continues to flow may be influenced by gravity; in other words by raising or lowering the baby relative to the placenta. Placental transfusion can give the baby about a fifth of its blood volume at birth, and so this may make a difference to the health and well‐being of a baby. Placental transfusion drains the blood left in the placenta, which may help the placenta separate from the womb and may reduce overall blood loss at birth for the woman. The review authors did not find any randomised trials which compare different positions for the baby between birth and cord clamping.

Background

Description of the condition

The third stage of labour is the time from birth of the infant until delivery of the placenta. During this period the woman is at risk of major blood loss (postpartum haemorrhage). Active management of the third stage of labour aims to reduce this risk. Traditionally, active management has included three components: use of a prophylactic uterotonic drug, cord clamping, and controlled cord traction. There is clear evidence that use of a prophylactic drug substantially reduces the risk of postpartum haemorrhage (Cotter 2001). The effects of the other components of active management remain uncertain: the comparative effects of alternative strategies for timing of cord clamping are unclear, for both term (McDonald 2008) and preterm birth (Rabe 2004), and the effects of controlled cord traction are unknown (Althabe 2006)

As soon as the baby is born, contraction of the uterus stops further exchange between fetal and maternal circulation. While the umbilical cord remains patent, blood may continue to flow between placenta and infant. Early clamping of the cord will restrict transfer of residual blood from the placenta to the infant. If clamping is deferred, the volume of this placental transfusion may be influenced by a range of other factors including gestation at birth, timing and choice of uterotonic, position of the baby (relative to the level of the placenta) before cord clamping, and whether it is a vaginal or caesarean birth (RCOG 2009).

The blood volume in the fetus, placenta and cord is approximately 110 ml per kg, although the distribution between fetus and placenta changes with gestational age (Linderkamp 1982; Wardrop 1995). At 30 weeks' gestation the split is about 50:50 between fetus and placenta. By term, this rises to about two‐thirds being in the fetus. Much of our understanding of the physiology of placental transfusion comes from studies conducted in the 1950s and 1960s (Dawes 1968; Gunther 1957; Yao 1968). Although many of these studies were elegant and informative, they relate to an era in which care during the first, second and third stages of labour was very different to current practice. Also, they provide few data relevant to caesarean or preterm birth.

The volume and duration of placental transfusion can vary considerably. For term births the mean volume of transfusion is reported to be around 90 ml (Yao 1968). About a quarter of the blood transfers in the first 10 to 15 seconds after birth (Yao 1968). If no uterotonic was used, placental transfusion was 90% complete after one minute, and complete after three minutes (Yao 1968). If methylergometrine was given (by intravenous injection) 15 to 30 seconds after birth of the baby, placental transfusion was complete after one minute. This is no longer recommended practice and oxytocin (intramuscular or intravenous) or intramuscular Syntometrine (oxytocin plus ergometrine) are now used as the prophylactic uterotonic drug (McDonald 2004; Prendiville 2000).

Gravity may also influence the volume and duration of placental transfusion. Raising or lowering the baby by 15 to 20 cm or more with the cord intact appears to influence placental transfusion (Gunther 1957; Yao 1969a), although in these studies use of a prophylactic uterotonic drug is not mentioned. Raising or lowering by 10 cm does not appear to influence placental transfusion (Lind 1965; Yao 1969b).

Description of the intervention

If the cord is not clamped immediately at birth, the volume and duration of placental transfusion may be influenced by raising or lowering the baby. Lifting the baby above the level of the placental bed will reduce flow away from the baby and into the placenta. Lowering the infant will increase flow to the baby. For term vaginal births, lowering the baby 40 cm below the mothers' introitus seems to lead to complete placental transfusion within 30 seconds (Linderkamp 1982; Yao 1969a). The threshold for influencing placental transfusion seems to be 10 to 15 cms, as raising or lowering by this amount does not appear to influence the volume or duration of placental transfusion (Gunther 1957; Yao 1969a).

Use of a prophylactic uterotonic drug to increase uterine retraction may, at least in part, help maintain placental transfusion despite the baby being lifted above the level of the introitus.

How the intervention might work

Alternative positions for the baby at birth before clamping the cord may influence placental transfusion. Increased placental transfusion leads to an increased blood volume at birth, which may facilitate transition from the fetal to the neonatal circulation. One hypothesis is that placental transfusion may provide the baby with additional circulating blood volume to support the expanding respiratory circulation. Also, it is important to understand whether influencing the duration of placental transfusion by lowering or raising the baby influences outcome.

For term infants, the increased neonatal blood volume associated with placental transfusion increases iron stores in early childhood (Chaparro 2006; McDonald 2008). Whether this improved iron status impacts on the child's health and development remains unclear (Hutton 2007; McDonald 2008). Iron deficiency may be associated with an increased risk of infection, impaired feeding, and impaired neurodevelopment (Grantham‐McGregor 2001; Harris 2007; Martins 2001). Potential adverse effects of placental transfusion for term infants are an increased risk of polycythaemia and clinical jaundice (Hutton 2007)

As placental transfusion allows drainage of the placental bed, which may encourage separation of the placenta, it may shorten the third stage of labour and facilitate delivery of the placenta. For example, placental drainage, where the cord is released to drain the placenta after clamping and cutting, is associated with a shorter third stage and a lower risk of retained placenta at 30 minutes (Soltani 2005). It seems plausible that it may also reduce blood loss and the need for manual removal of the placenta. Women may also have preferences for the care they receive during the third stage. Another potential impact for the mother is that if placental transfusion reduces infection and improves infant feeding, this in turn may lead to improved emotional well‐being of the mother, and fewer consultations with health service providers.

In utero, the distribution of blood between placenta and infant is proportional to fetal weight. For preterm births, placental transfusion may take longer and may provide a proportionally larger increase in the neonatal blood volume than at term births (Linderkamp 1982; UK 2006).

As so much of the fetal‐placental circulation is in the placenta for preterm infants, they have perhaps a greater potential to benefit from an increased placental transfusion than infants born at term. The greater neonatal blood volume may improve central and peripheral perfusion at birth. Preterm infants have an immature cardio‐respiratory system, making them slower than term infants to adapt to extra uterine life, and more susceptible to fluctuating blood pressure. The increased blood volume following placental transfusion may help stabilise both blood pressure and respiration, and improved perfusion may contribute to better temperature control, better renal function and less risk of intraventricular haemorrhage (Evans 1996; Rabe 2004; Rabe 2008; Yanowitz 1999).

Potential adverse effects of increased placental transfusion for preterm births are an increase in the risk of jaundice, and possibly a delay in transition to the neonatal circulation. There is also concern that deferred cord clamping may increase the risk of hypothermia.

Why it is important to do this review

Positioning of the baby between birth, either vaginal or caesarean, and cord clamping may influence the volume or duration of placental transfusion, or both. The impact of changes in placental transfusion on outcome for the baby and the mother remains unclear.

Objectives

To compare the effects of alternative positions for the baby before cord clamping, following vaginal or caesarean birth, in terms of outcomes for the baby, the mother and the health service.

Methods

Criteria for considering studies for this review

Types of studies

We included all randomised trials that compare different positions for the baby, relative to level of placenta, between birth and cord clamping. We excluded trials with a quasi‐random design.

Types of participants

Women before birth of the baby, regardless of gestation at birth and irrespective of mode of delivery.

Types of interventions

Studies would have been included if the interventions were different positions for the baby relative to the placental bed, with or without other interventions that might influence placental transfusion.

Types of outcome measures

For eligible studies, the following outcomes would have been included. Primary outcomes would have been used for subgroup analyses.

Primary outcomes

For the woman

1. Postpartum haemorrhage (defined where possible as > 500 ml).

2. Manual removal of placenta.

For the baby

1. Anaemia in early childhood (defined where possible as haemoglobin below 110 g/l).

2. Death: including perinatal death (stillbirth, deaths in the first week of life), neonatal death (deaths in the first 28 days of life) and infant deaths (deaths in the first year of life).

Secondary outcomes

For the woman

1. Blood loss at delivery (mean, standard deviation).

2. Length of third stage of labour (mean, standard deviation).

3. Need for blood transfusion.

4. Need for iron therapy in postnatal period.

5. Emotional well‐being (using any measure).

6. Breastfeeding (at discharge from hospital, at six weeks).

7. Women's views, including their preferences and measures of satisfaction.

8. Measures of costs to the health services, such as length of stay in hospital after delivery, number of GP visits postpartum, postnatal readmission to hospital.

For the baby

1. Haemoglobin (birth to four days, two to four months, mean and standard deviation).

2. Jaundice requiring phototherapy.

3. Temperature at birth (mean, standard deviation)

4. Blood transfusion.

5. Ferritin in early childhood (at two to four months of age, at six months of age).

6. Intraventricular haemorrhage (for babies born before 34 weeks gestation only, grade three or four on ultrasound).

7. Measures of costs to the health services: such as admission to neonatal care, length of stay on the neonatal unit, visits to primary care clinics, hospital admission.

8. Long‐term outcome: measures of growth (weight, height), neurodevelopment during childhood, and infection (diarrhoea, respiratory).

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 (July 2010).

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

1. quarterly searches of the Cochrane Central Register of Controlled Trials (CENTRAL);

2. weekly searches of MEDLINE;

3. handsearches of 30 journals and the proceedings of major conferences;

4. 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 each assigned to a review topic (or topics). The Trials Search Co‐ordinator searches the register for each review using the topic list rather than keywords. 

We did not apply any language restrictions.

Data collection and analysis

Selection of studies

Two review authors independently assessed each study identified during the search procedure for suitability for inclusion. Any differences in opinion were resolved by discussion. If agreement could not be reached, the third review author was consulted.

In future updates of this review, when data become available, we will use the prespecified methods for data collection and analysis. These are detailed in Appendix 1.

Results

Description of studies

We excluded 37 studies (7559 mother‐infant pairs). Of these, we excluded 33 studies (7296) because they did not compare alternative positions for the baby before clamping the umbilical cord; we excluded four studies (263) due to quasi‐random allocation (Canada 1972; Guatemala 1997; USA 1954; USA 1957). For further information about the excluded studies, seeCharacteristics of excluded studies. One additional trial is ongoing (USA 2008) (seeCharacteristics of ongoing studies).

Risk of bias in included studies

No trials were included.

Effects of interventions

Not applicable.

Discussion

Summary of main results

No studies met the inclusion criteria for this review.

Potential biases in the review process

We minimised potential biases by use of a comprehensive search strategy, and by all review authors independently assessing the quality of studies for inclusion and exclusion.

Agreements and disagreements with other studies or reviews

We are not aware of any other reviews on alternative positions of the baby at birth before cord clamping.

Authors' conclusions

Implications for practice.

Whether the baby is raised or lowered at birth whilst the cord is intact may influence the volume or duration of placental transfusion, or both, when cord clamping is deferred. There is promising evidence that allowing placental transfusion may improve outcome at discharge from hospital for both term (McDonald 2008) and preterm (Rabe 2004) births. The impact on longer‐term outcome is unclear (RCOG 2009). Position of the baby before cord clamping is one factor that may influence placental transfusion. It is of particular relevance to women, as many wish to either hold their baby or have the baby placed on their abdomen at birth. Currently, there is insufficient evidence to provide reliable advice as to whether or not this might influence placental transfusion, and if so whether this effect on placental transfusion might influence outcome for the mother or her baby.

In the absence of reliable data, women should be supported in their choice of where to place the baby between birth and cord clamping. Nevertheless, prudent advice would be that the baby should not be lifted more than 20 cm above the level of the introitus until after the cord is clamped (RCOG 2009).

Implications for research.

Large, well‐designed randomised trials are needed to assess whether gravity influences placental transfusion at vaginal and caesarean births and, if so, whether this affects short‐term and long‐term outcome for the baby and for the mother.

What's new

Date	Event	Description
13 December 2011	Amended	Contact details edited.

Appendices

Appendix 1. Methods to be used in future updates of this review

When data become available in future updates of this review, the following prespecified methods will be used for data collection and analysis.

Data extraction and management

A data extraction form has been designed. For eligible studies, two review authors will independently extract the data using the agreed form. Discrepancies will be resolved through discussion, or the third review author will be consulted. Data will be entered into Review Manager software (RevMan 2008) and checked for accuracy.

When information regarding any of the above is unclear, we will attempt to contact authors of the original reports to provide further details.

Assessment of risk of bias in included studies

Two review authors will independently assess risk of bias for each study using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2009). We will resolve any disagreement by discussion or by involving a third assessor.

(1) Sequence generation (checking for possible selection bias)

For each included study the method used to generate the allocation sequence should have been described in sufficient detail to allow an assessment of whether it will produce comparable groups.

Methods will be assessed as:

• adequate (any truly random process, e.g. random number table; computer random number generator);

• inadequate (any non‐random process, e.g. odd or even date of birth; hospital or clinic record number); or

• unclear.   

 (2) Allocation concealment (checking for possible selection bias)

For each included study the method used to conceal the allocation sequence, should have been described in sufficient detail to determine whether intervention allocation could have been foreseen in advance of, or during recruitment, or changed after assignment.

Methods will be assessed as:

• adequate (e.g. telephone or central randomisation; consecutively numbered sealed opaque envelopes);

• inadequate (open random allocation; unsealed or non‐opaque envelopes; alternation; date of birth);

• unclear.   

(3) Blinding (checking for possible performance bias)

We will describe for each included study the methods used, if any, to blind study participants and personnel from knowledge of which intervention a participant received. We will consider that studies are at low risk of bias if they were blinded, or if we judge that the lack of blinding could not have affected the results. We will assess blinding separately for different outcomes or classes of outcomes.

We will assess the methods as:·        

• adequate, inadequate or unclear for participants;

• adequate, inadequate or unclear for personnel;

• adequate, inadequate or unclear for outcome assessors.

(4) Incomplete outcome data (checking for possible attrition bias through withdrawals, dropouts, protocol deviations)

We will describe for each included study, and for each outcome or class of outcomes, the completeness of data including attrition and exclusions from the analysis. We will state whether attrition and exclusions were reported, the numbers included in the analysis at each stage (compared with the total randomised participants), reasons for attrition or exclusion where reported, and whether missing data were balanced across groups or were related to outcomes.  Where sufficient information is reported, or can be supplied by the trial authors, we will re‐include missing data in the analyses which we undertake. We will assess methods as:

• adequate;

• inadequate;

• unclear.

(5) Selective reporting bias

We will describe for each included study how we investigated the possibility of selective outcome reporting bias and what we found. We will assess the methods as:

• adequate (where it is clear that all of the study’s prespecified outcomes and all expected outcomes of interest to the review have been reported);

• inadequate (where not all the study’s prespecified outcomes have been reported; one or more reported primary outcomes were not prespecified; outcomes of interest are reported incompletely and so cannot be used; study fails to include results of a key outcome that would have been expected to have been reported);

• unclear.

(6) Other sources of bias

We will describe for each included study any important concerns we have about other possible sources of bias. We will assess whether each study was free of other problems that could put it at risk of bias:

• yes;

• no;

• unclear.

(7) Overall risk of bias

We will make explicit judgements about whether studies are at high risk of bias, according to the criteria given in the Handbook (Higgins 2009). With reference to (1) to (6) above, we will assess the likely magnitude and direction of the bias and whether we consider it is likely to impact on the findings.  We will explore the impact of the level of bias through undertaking sensitivity analyses ‐ see 'Sensitivity analysis'. 

Measures of treatment effect

Dichotomous data

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

Continuous data

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

Dealing with missing data

For included studies, we will note levels of attrition. We will explore the impact of including studies with high levels of missing data in the overall assessment of treatment effect by using sensitivity analysis.

For all outcomes, we will carry out analyses, as far as possible, on an intention‐to‐treat basis, i.e. we will attempt to include all participants randomised to each group in the analyses, and all participants will be analysed in the group to which they were allocated, regardless of whether or not they received the allocated intervention. The denominator for each outcome in each trial will be the number randomised minus any participants whose outcomes are known to be missing.

Assessment of heterogeneity

We will assess statistical heterogeneity in each meta‐analysis using the T², I² and Chi² statistics. We will regard heterogeneity as substantial if I² is greater than 30% and either T² is greater than zero, or there is a low P‐value (< 0.10) in the Chi² test for heterogeneity. 

Assessment of reporting biases

If there are 10 or more studies in the meta‐analysis we will investigate reporting biases (such as publication bias) using funnel plots. We will assess funnel plot asymmetry visually, and use formal tests for funnel plot asymmetry. For continuous outcomes we will use the test proposed by Egger 1997, and for dichotomous outcomes we will use the test proposed by Harbord 2006. If asymmetry is detected in any of these tests or is suggested by a visual assessment, we will perform exploratory analyses to investigate it.

Data synthesis

We will carry out statistical analysis using the Review Manager software (RevMan 2008). We will use fixed‐effect meta‐analysis for combining data where it is reasonable to assume that studies are estimating the same underlying treatment effect: i.e. where trials are examining the same intervention, and the trials’ populations and methods are judged sufficiently similar. If there is clinical heterogeneity sufficient to expect that the underlying treatment effects differ between trials, or if substantial statistical heterogeneity is detected, we will use random‐effects meta‐analysis to produce an overall summary if an average treatment effect across trials is considered clinically meaningful. The random‐effects summary will be treated as the average range of possible treatment effects and we will discuss the clinical implications of treatment effects differing between trials. If the average treatment effect is not clinically meaningful we will not combine trials.

If we use random‐effects analyses, the results will be presented as the average treatment effect with its 95% confidence interval, and the estimates of  T² and I².

Subgroup analysis and investigation of heterogeneity

If we identify substantial heterogeneity, we will investigate it using subgroup analyses and sensitivity analyses. We will consider whether an overall summary is meaningful, and if it is, use random‐effects analysis to produce it.

We plan to carry out the following subgroup analyses.

1. Gestation at trial entry: less than 34 weeks, 34 or more weeks, gestation mixed or unclear.

2. Mode of delivery: caesarean section, spontaneous vaginal, operative vaginal, mode of delivery mixed or unclear.

3. Timing of uterotonic: before cord clamping, after cord clamping, timing of uterotonic mixed or unclear.

4. Timing of cord clamping: before 30 seconds, after 30 seconds, timing of cord clamping mixed or unclear.

Subgroup analyses will be restricted to the primary outcomes.

For fixed‐effect inverse variance meta‐analyses we will assess differences between subgroups by interaction tests. For random‐effects and fixed‐effects meta‐analyses using methods other than inverse variance, we will assess differences between subgroups by inspection of the subgroups’ confidence intervals; non‐overlapping confidence intervals indicate a statistically significant difference in treatment effect between the subgroups.

Sensitivity analysis

We will carry out sensitivity analysis, where appropriate, to explore the effects of trial quality. We will exclude studies of poor quality, as assessed by concealment of allocation, from the analysis in order to assess for any substantive difference to the overall result. If no substantive difference exists, the studies will be left in for the main analysis. For concealment of allocation, we will exclude studies with clearly inadequate allocation of concealment (rated inadequate). We will conduct this sensitivity analysis for the primary outcomes only.

Characteristics of studies

Characteristics of excluded studies [ordered by study ID]

Study	Reason for exclusion
Argentina 2004	Wrong intervention: no alternative positions for the deferred cord clamped groups. Interventions: cord clamping at 1 minute versus 3 minutes versus cord clamping within 15 seconds. Participants: 276 neonates born at term without complications; vaginal and caesarean births.
Australia 1990	Wrong intervention: early cord clamping versus early cord clamping with placental drainage. Participants: 1908 women vaginal birth and active management of the third stage of labour.
Australia 1997	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: cord clamping at 30 seconds versus immediate cord clamping. Participants: 46 mother‐infant pairs, gestational age 26 to 33 weeks.
Canada 1965	Wrong intervention: no alternative positions for the deferred cord clamped group. Not a randomised trial, infants randomised by "random selection". Interventions: cord clamping at 5 minutes with infant held 15 cm below the introitus versus cord clamping 5 seconds after birth. Participants: 32 mother‐infant pairs, gestational age 38 to 44 weeks.
Canada 1972	Trial, with quasi‐random design, of immediate versus deferred cord clamping, using sequential allocation. Those allocated a 1 minute delay were again divided by sequential allocation to being held above or below the perineum. Interventions: cord clamping either immediate, at 1 minute or at 5 minutes. For those allocated a 1 minute delay, further allocation to holding the baby 30 cm below perineum or 15 cm above perineum. Participants: 170 mother‐infant pairs, gestational age 28 to 42 weeks. Numbers allocated a 1‐minute delay not reported.
Canada 1980	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: cord clamping at cessation of cord pulsation with Leboyer approach to birth versus cord clamping within 60 seconds. Participants: 55 mother‐infant pairs.
Finland 1984	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: cord clamping at 1.5 minutes versus cord clamping at 3 minutes versus immediate cord clamping. Participants: 19 mother‐infant pairs, elective caesarean section births.
Germany 1992	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: cord clamping at 3 minutes versus cord clamping within 10 seconds. Participants: 30 mother‐infants pairs, gestational age 39 to 40 weeks, vaginal births.
Germany 1993	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: cord clamping at 3 minutes with Leboyer approach to birth versus cord clamping within 10 seconds. Participants 30 mother‐infant pairs, vaginal births.
Germany 1996	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: cord clamping at 20 seconds versus cord clamping at 45 seconds. Participants: 39 preterm infants, gestational age less than 33 weeks.
Germany 1998	Wrong intervention: no alternative positions for the deferred cord clamped group. Intervention: cord clamping at 30 seconds, infant held 30 cm below placental level versus early cord clamping. Participants: 19 mother‐infant pairs, caesarean births.
Guatemala 1997	Quasi‐random design, using days of the week for allocation, with 19% of infants lost to follow up. There were missing data for an additional 5% of infants. Interventions: clamping at cessation of cord pulsation, infant held at placental level versus cord clamping at cessation of cord pulsation, infant held below placental level versus early cord clamping. Participants: 69 mother‐infant pairs, vaginal births.
India 1997	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: cord clamping following decent of placenta into the vagina, infant held below introitus versus immediate cord clamping. Participants: 107 mother‐infant pairs, term, vaginal birth.
India 2001	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: cord clamping following decent of placenta into the vagina, infant held below introitus versus immediate cord clamping. Participants: 102 mother‐infant pairs; women with haemoglobin < 100 g/L at delivery with no associated medical or obstetric problems.
Iran 2005	Wrong intervention: active versus physiological management of the third stage of labour. Participants: 94 mother‐infant pairs, vaginal births.
Iran 2008	Wrong intervention: no alternative positions for the delayed cord clamped group. Intervention: cord clamping at 3 minutes versus early cord clamping at 30 seconds. Participants: 64 mother‐infant pairs, gestational age 38 to 42 weeks, vaginal births.
Israel 2007	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: cord clamping at 30 to 45 seconds infant held 20 to 30 cm below the level of the introitus/incision versus immediate cord clamping, 5 to 10 seconds after birth. Participants: 65 mother‐infant pairs, gestational age 24 to 35 weeks, vaginal and caesarean births.
Japan 2008	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: early cord clamping versus cord clamping following cord milking. Participants: 40 infants gestational age 24 to 28 weeks, vaginal and caesarean births.
South Africa 1960	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: cord clamping after signs of placental separation and cord stripping versus infant held below level of uterus versus early cord clamping, within 15 seconds. Participants: 133 mother‐infant pairs, vaginal births at term.
South Africa 1991	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: cord clamping at 1 to 2 minutes versus immediate cord clamping. Participants: 86 infants weight less than 2 kg.
Sweden 1970	Wrong intervention: no alternative positions for the deferred cord clamped group. Quasi‐random study, participants consecutively allocated to intervention or control. Interventions: cord clamping at 5 minutes, infant 20 cm below the placenta versus cord clamping within 10 seconds. Participants: 14 term mother‐infant pairs, vaginal births.
Switzerland 2007	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: cord clamping at 60 to 90 seconds, infant held below placenta versus cord clamping within 20 seconds. Participants: 39 mother‐infant pairs, gestational age 24 to 32 weeks, caesarean and vaginal births.
UK 1966	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: cord clamping at 3 to 10 minutes versus cord clamping at 0 to 3 seconds. Participants: 22 infants of Rh positive mothers, born vaginally.
UK 1988	Wrong intervention: active versus physiological management for the third stage of labour. Participants: 1695 women expected to give birth vaginally.
UK 1993a	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: cord clamping at 25 to 35 seconds, infant held 20 cm below introitus versus cord clamping within 20 seconds. Participants: 36 mother‐infant pairs, gestational age 27 to 33 weeks, vaginal births.
UK 1993b	Wrong intervention: active versus physiological management of the third stage of labour. Participants: 193 mother‐infant pairs, low risk of postpartum haemorrhage.
UK 1996	Wrong intervention: active versus physiological management of the third stage of labour. Interventions: active management, upright or supine position versus physiological management, upright versus supine position. Participants: 1512 mother‐infant pairs, low risk of postpartum haemorrhage.
UK 1998	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: cord clamping at 40 to 90 seconds, infant held below the placenta versus immediate cord clamping. Participants: 150 mother‐infant pairs, gestational age less than 32 weeks.
UK 2006	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: cord clamping at 30 to 90 seconds, infant held low, versus immediate cord clamping. Participants: 46 mother‐infant pairs, gestational age 24 to 33 weeks.
USA 1954	Quasi‐random study, with 4 arms. Outcome data presented as mean and range, standard deviation not reported. Interventions: cord clamping after cessation of pulsation, infant held above placenta versus cord clamping after cessation of pulsation, infant held below placenta versus cord clamping after 4 to 8 cord strippings, infant held below placenta versus immediate cord clamping. Participants: 100 term mother‐infant pairs.
USA 1957	Quasi‐random design ("in rotation") for comparison of level of baby. Interventions: cord clamping at 3 minutes, infant below the introitus versus cord clamping at 3 minutes, infant on the mother's abdomen versus cord clamping following cord milking, infant on the lap of the obstetrician versus immediate cord clamping. Participants: 38 term mother‐infant pairs, vaginal births.
USA 1963	Wrong intervention: no alternative positions for the deferred cord clamped group. Quasi‐random, alternate group allocation. Interventions: cord clamping 1 to 3 minutes after birth versus early cord clamping within 1 minute. Participants: 182 mother‐infant pairs at term and 340 preterm (less than 2500 g birthweight), vaginal births.
USA 1984	Wrong intervention: no alternative position for the deferred cord clamped group. Interventions: Leboyer approach to birth with cord clamping within 60 seconds versus Leboyer approach to birth with cord clamping at 10 minutes versus cord clamping within 60 seconds. Participants: 91 mother‐infant pairs, vaginal births.
USA 2000	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: cord clamping at 20 second, infant held supine at the level of the introitus versus immediate cord clamping. Participants: 32 mother‐infant pairs, gestational age 24 to 29 weeks.
USA 2003a	Wrong intervention: no alternative positions for the deferred clamped group. Interventions: cord clamping 30 to 45 seconds after birth versus immediate cord clamping, 5 to 10 seconds. Participants: 32 mother‐infant pairs, gestational age 24 to 32 weeks.
USA 2003b	Wrong intervention: no alternative positions for the deferred cord clamped group. Interventions: cord clamping at 60 seconds versus cord clamping at 2 to 5 seconds. Participants: 35 mother‐infant pairs, gestational age less than 36 weeks, vaginal and caesarean births.
USA 2005	Wrong intervention: no alternative position for the deferred cord clamped group Interventions: cord clamping at 30 to 45 seconds, with infant held below the introitus, versus cord clamping within 10 seconds Participants: 72 mother‐infant pairs, gestational age less than 32 weeks, vaginal and caesarean births

Characteristics of ongoing studies [ordered by study ID]

USA 2008.

Trial name or title	Effect of infant placement on iron stores in infancy: a pilot study.
Methods	Type of study: single centre randomised trial, single‐blind. Method of treatment allocation: parallel assignment, stratification not stated. Placebo: no. Sample size: not stated. Funding: not stated.
Participants	Included: infants born vaginally, 37 to 42 weeks' gestational age. Excluded: mothers with diabetes and hypertension, infants that are growth restricted.
Interventions	Infant held at perineal level. Infant held at abdominal level.
Outcomes	Primary: infant serum ferritin at 4 months. Secondary: infant haemoglobin, hematocrit and serum ferritin at 2 months, haemoglobin and hematocrit at 24 hours.
Starting date	June 2008.
Contact information	James Davison, Warren General Hospital, USA.
Notes	—

Differences between protocol and review

The Background and Methods section of this review have been amended in response to editorial feedback and in accordance with the latest Cochrane handbook Higgins 2009.

In response to the editors feedback we have reduced the number of secondary outcomes. For the baby, Hematocrit and need for ventilation have been removed.

Contributions of authors

All three authors were involved in the planning and development of the protocol. Rebecca Airey (RA) and Diane Farrar (DF) assessed studies for quality; any disagreements were resolved with the input of the third author Lelia Duley (LD). RA formulated the first draft of the review. DF and LD commented on drafts of the review.

Sources of support

Internal sources

• University of Leeds, UK.

• Bradford Teaching Hospitals NHS Foundation Trust, UK.

External sources

• No sources of support supplied

Declarations of interest

None known.

Edited (no change to conclusions)