Standard practice for preterm babies is to cut the cord as soon as possible, often within 10 to 15 seconds.
A systematic review finds that delaying the clamping rather than doing it immediately also reduces anemia and increases blood pressure and blood volume, helping preterm infants off to a healthier start in life, says lead study author Heike Rabe, M.D., Ph.D. of Brighton and Sussex University Hospitals in Brighton, England.
"If the cord is left unclamped for a short time after the birth, some of the baby's blood from the placenta passes to the baby to help the flow of blood to the baby's lungs," Rabe explains. "Delaying cord clamping for just a very short time helped the babies to adjust to their new surroundings better."
The review appears in the October issue of the Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.
Medical staff ordinarily clamp the umbilical cord in two places after the baby is delivered, then cut the cord between the two clamps.
"I'm comfortable with the 30-second delay, but there are so many things that can happen with a preterm infant that doctors have to use their judgment in each case," says neonatologist Tonse N. K. Raju, M.D., D.C.H., of the National Institute of Child Health and Development in Bethesda, Md.
The seven studies in Rabe's systematic review covered 297 infants. The studies measured blood pressure, red blood cell counts, blood volume, bleeding within the brain and the need for transfusions.