Delayed cord clamping and improved infant outcomesBMJ 2011; 343 doi: http://dx.doi.org/10.1136/bmj.d7127 (Published 15 November 2011) Cite this as: BMJ 2011;343:d7127
- Patrick van Rheenen, consultant paediatrician
Cord clamping and cutting is a common procedure but little agreement exists among doctors about the optimal timing. Cord clamping takes place in the third stage of labour, which is defined as the period from expulsion of the fetus to the expulsion of the placenta. Early clamping in term babies is sometime between 10 seconds and one minute after birth, whereas delayed clamping is between two minutes after birth and cessation of cord pulsations. In the linked randomised trial (doi:10.1136/bmj.d7157), Andersson and colleagues compare the effects of early versus delayed cord clamping on infant iron status at 4 months of age in a European setting.1
Management of the third stage of labour has typically focused on women and prevention of postpartum haemorrhage. A systematic review published in 2000 found that active management involving the use of oxytocics, early cord clamping, and controlled cord traction was superior to expectant management in terms of maternal blood loss.2 For this reason, early clamping was accepted into obstetric practice without much consideration.
Another systematic review published in 2008 studied the effects of different cord clamping times on maternal blood loss and found that delayed clamping poses no additional threats to women.3 These results should have paved the way for a more liberal approach to delaying clamping in uncomplicated term deliveries. Yet immediate clamping and cutting of the umbilical cord continues to be a routine part of the active management package. Recently published surveys among obstetricians and midwives in the United Kingdom show that more than 95% of respondents clamp before two minutes and pass the baby off as quickly as possible.4 5
Immediately after a baby is born placental blood continues to flow in the direction of the child as long as he or she is positioned up to 10 cm above the level of the placenta. The additional blood volume transferred to the infant after birth is called placental transfusion. For a term infant, placental transfusion increases the total volume of blood by about 30%. Within a few hours the additional plasma is lost to the circulation, leaving a high red cell mass. This is broken down in the first two months of life and the iron is re-used or stored.
In the 1970s, paediatricians recommended early cord clamping, because of fears that over-transfusion caused polycythaemia, hyperviscosity syndrome, or hyperbilirubinaemia. However, a recent high quality meta-analysis of randomised controlled trials from the past 15 years convincingly showed that delayed cord clamping in full term neonates for a minimum of two minutes is beneficial to the newborn, and that this benefit extends into infancy.6 Benefits include improved haematological status—measured as haematocrit value, ferritin concentration, and stored iron—and a clinically important reduction in the risk of anaemia. An increase was seen in polycythaemia, but it seemed to be benign. No significant differences were seen between delayed and early cord clamping in the risk of neonatal jaundice. Because many of the included trials were from resource poor countries with a high prevalence of infant anaemia, the applicability of delayed clamping in developed countries was questioned.
Andersson and colleagues present a well designed and executed randomised controlled trial on the timing of cord clamping in 400 infants in Sweden, a country with a low prevalence of iron deficiency anaemia.1 The study found that delayed cord clamping significantly improved iron status and reduced the prevalence of anaemia and iron deficiency at 4 months of age. No significant difference was seen in adverse effects between the groups.
Although paediatricians think that early cord clamping is needed in infants who require immediate neonatal resuscitation, these cases are exceptions. Most newborn infants do not require resuscitation—immediate drying and keeping them warm is all that is needed. Less than 10% of newborns need help to start breathing at birth (stimulation, positioning, clearing the airway), and about 1% need extensive resuscitation. When respiratory efforts are absent or inadequate despite initial stabilisation, inflation breaths by mask ventilation are the priority.7 The earliest time to assess whether these inflation breaths are successful is about 60 seconds after delivery. All these steps can be done while the umbilical cord is intact (see figure⇓). Immediate cord clamping to enable resuscitation away from the mother could deprive the infant of much needed extra blood volume, and the resulting hypovolaemia might adversely affect tissue perfusion. Furthermore, as long as the uterus is not contracting and the placenta has not been detached, the infant may still receive oxygen via the intact placental-fetal circulation.
No evidence is available on whether infants deprived of placental blood have poorer neurodevelopment than those who receive placental transfusion. This is why Andersson and colleagues emphasise the importance of exploring the long term effects on health of delayed and early cord clamping. The time to cord clamping should therefore be documented for all future births, especially in studies with a neurodevelopmental end point.
The balance of maternal risks and infant benefits of delayed cord clamping now clearly favours the child. How much more evidence is needed to convince obstetricians and midwives that it is worth while to wait for three minutes to allow for placental transfusion, even in developed countries? Andersson and colleagues’ study is convincing enough to encourage a change of practice.
Cite this as: BMJ 2011;343:d7127
Competing interests: The author has completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declares: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.
Provenance and peer review: Commissioned; not externally peer reviewed.