Leaving umbilical cord attached for a few minutes allows the blood in the cord to transfer to the baby, according to a study published in The Cochrane Library.
In many countries, it’s standard practice to clamp the umbilical cord connecting mother and baby less than a minute after birth.
But cutting the cord too soon may reduce the amount of blood that passes from mother to baby via the placenta–affecting the baby’s iron stores. On the other hand, delayed cord clamping, which is carried out more than a minute after birth, may also increase the risk of jaundice.
The World Health Organisation now recommends cord clamping between one and three minutes after birth.
The role of the umbilical cord, which connects the mother to her child in the womb, is to provide a source of nutrients directly to the unborn baby.
The existing guidance on cord-clamping was published in 2007 when the consensus was that cutting the cord immediately was the best option, something which had been the case for decades. But since then researchers have questioned whether that is still the case.
The latest study involving 3,911 women and their babies showed clamping the cord later made no difference to the risk of maternal haemorrhaging, blood loss or haemoglobin levels and babies were healthier in a number of respects.
When cord cutting was delayed babies had higher haemoglobin levels between one and two days after birth and were less likely to be iron deficient three to six months after birth.
Birth weight was also higher with delayed cord clamping. Clamping the cord later leads to a slightly higher number of babies needing treatment for jaundice–treated by light therapy.
Experts say the benefits of delayed cord clamping need to be weighed against the small additional risk of jaundice in newborns. Later cord clamping to increase iron stores might be particularly beneficial in settings where severe anaemia is common.