Waiting 30 seconds to two minutes after birth to cut the umbilical cord of a premature baby appears to lessen chances of bleeding in the newborn’s brain and reduce the need for transfusions, according to a new review of research.
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.
Since 60 percent to 80 percent of preterm infants less than 32 completed weeks’ gestation require transfusion, strategies that might reduce this without risk would be desirable, says Rabe. Decreasing the need for transfusion would be especially valuable in developing countries, where transfusion carries a high risk of transmitting infection.
No formal guidelines currently set the time for clamping the cord. The American College of Obstetricians and Gynecologists says it does not take a position on the timing of cord clamping, citing “insufficient evidence.”
However, pre-term infants (those born at 24 to 37 weeks) often have trouble breathing, so physicians prefer moving them immediately to intensive care units where they are helped to breathe. Moving the baby requires clamping and cutting the umbilical cord quickly.
“The acceptable range of red blood cell levels or blood pressure in preterm infants is so narrow that even seconds can make an important difference,” Raju says. Despite this importance, evidence is sparse.
“Clamping time is seen as so unimportant that it’s not even recorded on hospital charts, which makes it hard to do even retrospective studies,” says Judith Mercer, C.N.M., D.N.Sc., of the University of Rhode Island, who has studied the issue.
Despite concerns for the baby’s respiratory status, the trials covered in the review offered little guidance about how breathing is affected by cord clamping time, Rabe says. “At least there was no negative effect on babies’ breathing after delaying the clamping of the cord.”