In wealthier nations it is common practice to clamp the baby's umbilical cord less than a minute after birth. But a recent review of published studies suggests delaying cord clamping results in healthier blood and iron levels in babies, and this benefit outweighs the slightly higher risk of developing jaundice.

The reviewers arrived at this conclusion after analyzing data on nearly 4,000 women and their babies. They report their findings online in a July 11th issue of the Cochrane Database of Systematic Reviews.

One of the authors, Philippa Middleton of the Australian Research Centre for Health of Women and Babies at the University of Adelaide, says in a statement:

"In light of growing evidence that delayed cord clamping increases early haemoglobin concentrations and iron stores in infants, a more liberal approach to delaying clamping of the umbilical cord in healthy babies appears to be warranted."

In higher income countries, the standard practice is to clamp the umbilical cord within a minute of the baby being born.

If cord clamping is delayed, the risk that the baby will develop jaundice rises. Newborns with jaundice are treated with light therapy.

However, stopping the blood from the placenta reaching the baby before the final few pulses stop, means there is a chance the baby will not receive enough blood from the mother and will have lower iron levels.

Middleton says they did find that clamping the cord later was linked to higher numbers of babies needing treatment for jaundice, however, she urges that:

"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"

The researchers reviewed 15 trials comparing early and late cord clamping covering a total of 3,911 women and their infants.

They examined results for mothers and babies separately, using haemoglobin measures as indicators of healthy blood and iron levels.

Although another reason sometimes given for early cord clamping is that it reduces the mother's risk of bleeding after birth, the reviewers found no evidence of this.

Benefits of delayed cord clamping did not come with any increased risks

Delayed cord clamping did not change the mother's risk of haemorrhaging, losing blood or having reduced haemoglobin levels, they note.

But delaying cord clamping did make a difference to the health of the babies. Between one and two days after birth, their haemoglobin levels were higher; between three and six months after birth, they were less likely to be deficient in iron.

The reviewers also found that delayed cord clamping was linked to higher birth weight and made no difference to deaths in newborns.

They also found delayed cord clamping appears to have no effect on longer-term brain development, although only one of the trials examined this.

The reviewers conclude their findings suggest we need to adopt a "more liberal approach" to delaying cord clamping which is likely to benefit babies, "as long as access to treatment for jaundice requiring phototherapy is available".

The World Health Organization recommends cord clamping between one and three minutes after birth.

This review only included babies born full term. However, another review published in the same journal in 2012 found that delayed cord clamping also benefits preterm babies.

Two studies published in The Lancet suggest that cleansing the umbilical cord is also vital for newborn health and survival.

Written by Catharine Paddock PhD