Iron deficiency in children is a major problem in developing countries, but it can also affect kids closer to home. Iron is critical for brain development, so it’s a serious concern in the medical community.

Historically, doctors clamped the umbilical cord in the first few seconds of a newborn’s life. But waiting a little longer to clamp it — two to three minutes — has been shown to improve iron levels, since it allows blood in the placenta to circulate back into the infant.

The authors of a new study built on this earlier research and wondered if waiting longer to clamp the cord might also affect neurodevelopment years later.

Boys who’d had delayed clamping had better social skills and fine motor skills at four years old.

For four years, the researchers followed children who’d had their cords clamped immediately and kids who’d had delayed clamping. The children’s parents and caregivers filled out questionnaires about the child's behavior, development, motor, and social skills. The researchers also gave the children IQ tests. Just over 260 children and their families took part in the study.

It turned out that for girls, there weren’t any differences in those whose umbilical cords had been clamped immediately or delayed. But boys who’d had delayed clamping had better social skills and fine motor skills at four years old. They didn’t have any differences in IQ or other areas of development, however.

The team, from Uppsala University in Sweden, is optimistic about their findings, particularly since the study was made up of a group of low-risk children born in a high-income country with a low prevalence of iron deficiency. In children from higher-risk countries, the results might be even more pronounced, they believe. In addition, the authors say, there were no adverse effects from the iron.

So is it time for doctors to start changing their practices when it comes to cord clamping? Experts from Brighton and Sussex Medical School and University Hospitals who were not involved in the study, applaud the persistence of the new research for following the kids for four years.

In an accompanying editorial, they said it is time to stop the immediate clamping habit, provided the benefits of delayed clamping — and lack of negative effects.

More research will be needed, of course, but in the meantime, obstetricians should consider delayed clamping in their practice, both in developed countries, and in the places where iron deficiency is even more serious a problem. And always have your child’s iron levels tested as the current recommendations suggest.

The study is published in JAMA Pediatrics.