Children developed better fine-motor skills when the clamping of their umbilical cord at birth was delayed several minutes compared with just seconds, according to a new randomized trial.

Delaying clamping allows fetal blood circulating in the placenta to be transfused to the infant, which has been shown to reduce iron deficiency at four to six months of age. Now the longer term benefits of a delay are becoming clearer.

Researchers in Sweden randomly assigned 382 full-term infants born after low-risk pregnancies to be clamped at least three minutes after delivery or within 10 seconds of birth.

When the children were four, a psychologist assessed them on standard tests of IQ, motor skills and behaviour. The parents also filled in questionnaires about their child's communication and social skills.

"Delayed cord clamping compared with early cord clamping improved scores and reduced the number of children having low scores in fine-motor skills and social domains," the study's lead author, Dr. Ola Andersson of Uppsala University in Sweden, and his co-authors said in Tuesday's issue of JAMA Pediatrics.

The fine-motor skill tests showed those in the delayed clamping group had a more mature pencil grip.

There was also a difference in boys, who researchers said are generally more prone to iron deficiency than girls. Boys showed more improvements in fine-motor skills with delayed clamping.

Andersson said delayed cord clamping can have quite an effect on the amount of iron in the blood, which is important for brain development just after birth.

Simple, no-cost intervention

In 2013, the respected Cochrane Collaboration, an international network of scientists who regularly review medical research, concluded: "A more liberal approach to delaying clamping of the umbilical cord in healthy term infants appears to be warranted."

In a journal editorial published with the new study, Dr. Hieki Rabe of the Brighton and Sussex Medical School in England and her co-authors concluded "the potential benefit of improving maternal and neonatal care by a simple no cost intervention of delayed [cord clamping] should be championed by the international community."

So far, Canadian midwives commonly delay cord clamping. The World Health Organization recommends waiting at least one minute after birth, or until visible pulsing stops, to clamp the umbilical cord. In 2012, the American College of Obstetricians and Gynecologists opinion, said it supports delayed cord clamping for premature infants, but said there is insufficient evidence to prove a benefit for full-term babies.

In medical circles, cord clamping has been common for about 60 years under the mistaken belief it could reduce the risk of hemorrhage. It's a psychological hurdle for doctors to change the practice, Rabe said.

The researchers noted the results applied to a low-risk population of children born in a high-income country.

"If you did the same study in India you might see a marked difference, the reason is that there is excellent nutrition in Sweden," Rabe said.

There are still questions about cord clamping, such as the ideal time to wait, best position to hold the infant and the role of milking the cord as an alternative, the editorial writers said.

A limitation of the study is the drop out, or attrition, rate among participants was relatively high at about 31 per cent.