Shortly after a baby is born, doctors clamp the umbilical cord linking the infant to the placenta, which is still inside the mother’s uterus, and then cut it. New research shows that if doctors wait at least two minutes after the birth to clamp the cord, they significantly improve in-hospital survival rates for premature infants.
Delayed cord clamping — an intervention that can be introduced at relatively little cost — is believed to help because it allows umbilical cord blood, which is rich in iron, stem cells and antibodies, to flow back to the baby. Some experts say that it’s not entirely clear why the strategy seems to help, but that the data is convincing.
How It Works: Doctors wait to cut the cord.
The American College of Obstetricians and Gynecologists already recommends delaying clamping by 30 to 60 seconds for both full-term and preterm newborns.
Preterm babies are those born before 37 weeks of gestation. In preterm infants, delayed clamping leads to improved circulation, less need for blood transfusions and a lower incidence of serious complications, such as necrotizing enterocolitis, or inflammation of the digestive tract.
The evidence about whether the practice is beneficial for them has been inconsistent, according to Anna Lene Seidler, lead author of two new review papers and a senior research fellow at the University of Sydney in Australia.
The new research also sought to determine the optimal time to wait before clamping. The longest delays that were studied were three minutes after birth.
“We found that the longer we wait, the better, and the more we can reduce mortality,” Dr. Seidler said. “We were astounded by how consistent the findings are.”
Two new papers, published in The Lancet, analyzed dozens of studies involving thousands of babies born in hospitals in a range of countries, including Britain, India, Iran and the United States.
The Numbers: A two-minute postponement seems optimal.
One of the reviews compared the effectiveness of three techniques: immediate cord clamping, deferred clamping and milking an intact umbilical cord so that more blood flowed to the newborn.