Babies have a lower risk of developing iron deficiency anaemia at four months when there is a delay in clamping the umbilical cord after delivery, a study from Sweden has shown.

A total of 400 term babies were randomised to early cord clamping (within 10 seconds of birth) or delayed clamping (at least three minutes after delivery). Babies were held 20 cm below the level of the perineum to aid flow of blood from the placenta to the baby before division of the cord. The primary outcome was iron status and the secondary outcomes were neonatal morbidity including anaemia, polycythaemia, the need for phototherapy and respiratory symptoms.

At four months, there were no differences in haemoglobin levels between the two groups. However, mean ferritin levels were 117 and 81 µg/L, in delayed and early clamped babies, respectively, a difference of 45% (95% CI: 23%-71%, p < 0.001).

The relative risk reduction was 0.9, and number needed to treat (NNT) to prevent one case of iron deficiency was 20.

Neonatal anaemia was more common in the early clamped than the late clamped babies, 6.3% compared with 1.2%, respectively, p = 0.02. The relative risk reduction was 0.8, and NNT to prevent one case was 20.

Although anaemia rates were similar by four months of age all measures of iron stores were significantly lower in the early clamped babies.

In this affluent developed world community no adverse effects of early clamping were noted. Respiratory distress and the need for phototherapy were equally uncommon in both groups. No baby in either group had polycythaemia.

Usual practice during both vaginal and abdominal delivery is to double clamp and cut the umbilical cord within seconds of delivery. This, it is said, avoids overloading the baby with blood from the placenta reducing the risk of neonatal jaundice and respiratory distress.

Iron is necessary for brain development and deficiency is associated with poor motor development and lasting cognitive delay. Early clamping prevents a significant volume transfusion of blood from the placenta to the baby at birth compromising iron stores. Worldwide this is a massive problem, perhaps compounded by the lack of iron in mothers’ milk. This study found no harm but revealed a significant effect on iron status at four months in babies whose cord was clamped straight after delivery. Perhaps Mother Nature knows best.

Dr Chris Barclay

• Andersson O, Hellström-Westas L, Andersson D, Domellöf M. Effect of delayed versus early umbilical cord clamping on neonatal outcomes and iron status at 4 months: a randomised controlled trial. BMJ 2011;343:d7157