Science Update: Delayed cord clamping may benefit infant brain development, NIH-funded study finds

Fetus floating in the womb, tethered to its umbilical cord.
Credit: Stock Image

A 5-minute delay in clamping the umbilical cord after birth may benefit an infant’s developing brain, suggests a small study funded by the National Institutes of Health. The delay, which is a change from the traditional practice of clamping and cutting the cord immediately after birth, allows iron-rich red blood cells to flow from the placenta into the infant’s circulatory system. By 4 months of age, the brains of infants in the study who underwent delayed clamping had more myelin, a brain-insulating material, compared to those whose cords were clamped within 20 seconds. Myelin, which accelerates communication in the brain, is produced by iron-dependent brain cells.

The study, appearing in The Journal of Pediatrics, was conducted by researchers at the University of Rhode Island in Kingston and other institutions. Funding was provided by NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development and National Institute of Mental Health and by the Bill & Melinda Gates Foundation.


Traditionally, practitioners have clamped the umbilical cord immediately after birth. Previous studies have shown that delaying cord clamping results in a 20 to 30 percent increase in an infant’s blood volume. Researchers were concerned that this extra blood volume might place infants at risk of high bilirubin levels (jaundice)—a potentially serious condition resulting from the breakdown of extra blood cells. Another concern was that delayed clamping could result in an excess of red blood cells, which might slow circulation. Previous studies have suggested, however, that delayed clamping could have benefits, including a lower risk of iron deficiency and a better flow of red blood cells to the kidneys and brain.

In a previous study, authors reported that, by 48 hours of age, infants who had been randomly assigned to a 5-minute delay in cord clamping at birth had higher levels of hemoglobin (a red blood cell protein), but were no more likely than infants undergoing immediate cord clamping to have excess levels of bilirubin or red blood cells.

For the current study, which looked at the same population of infants, researchers theorized that the greater volume of iron from high levels of red blood cells among infants undergoing delayed cord clamping might result in a higher brain concentration of myelin.


Researchers obtained MRI scans of 44 of the 73 participants from the original study when they were 4 months of age. Infants who underwent delayed cord clamping had higher levels of myelin in brain regions associated with motor, visual, and sensory functioning and processing. They also had higher serum levels of ferritin, a protein that stores iron. The researchers found no difference between the two groups, however, in scores on a test of visual, gross and fine motor, and language skills.


"Our study shows that waiting 5 minutes or more before clamping the umbilical cord, while infants are held skin-to-skin with the mother, leads to more myelin development," said study author Debra Erickson-Owens, Ph.D., of the College of Nursing, University of Rhode Island in Kingston. "This is a low-tech, low-cost technique that we believe can mitigate iron deficiency and vulnerability to anemia.

Next Steps

In future publications, the researchers plan to describe results of assessments of the study participants at 12 and 24 months of age.


Mercer, JS, et al. Effects of delayed cord clamping on 4-month ferritin levels, brain myelin content, and neurodevelopment: a randomized controlled trial. The Journal of Pediatrics. .

top of pageBACK TO TOP