A technique to increase the flow of blood from the umbilical cord into the infant’s circulatory system improves blood pressure and red blood cell levels in preterm infants delivered by cesarean section, according to a study funded by the National Institutes of Health.
The technique, known as cord milking, consists of encircling the cord with thumb and forefingers, gently squeezing, and slowly pushing the blood through the cord to the infant’s abdomen. For infants delivered by cesarean, cord milking appears to offer benefits over the standard practice of waiting 45 to 60 seconds before clamping and then cutting the umbilical cord. These benefits, which include greater blood flow to and from the heart, higher red blood cell level, and higher blood pressure, were seen only in the infants delivered by cesarean. Among a smaller number of vaginal births, the researchers found no difference in blood volume between infants undergoing cord milking and those undergoing delayed cord clamping.
Delaying umbilical cord clamping by 30 to 60 seconds is thought to allow sufficient time for blood from the umbilical cord to fill the blood vessels in the infant’s lungs, Dr. Tonse Raju, chief of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Pregnancy and Perinatology Branch, said. Among preterm infants, the delay is believed to protect from intraventricular hemorrhage, or bleeding in the ventricles — the cavities inside the infant’s brain. The hemorrhage is thought to result from low blood pressure, brought on by having too little blood in the circulatory system. Bleeding in the brain may result in developmental delays, cerebral palsy, and in severe cases, death.
However, Dr. Anup C. Katheria, M.D., a neonatologist at the Neonatal Research Institute at the Sharp Mary Birch Hospital and the study’s first author, noted that some studies failed to find a reduction in intraventricular hemorrhage from delayed cord clamping among preterm infants delivered by cesarean. The scientists theorized that the use of an anesthetic in cesarean delivery reduces uterine contractions, and in so doing hinders the exodus of blood from the umbilical cord. Cord milking, they reasoned, might compensate for diminished blood flow through the umbilical cord and increase the amount of blood available to the infant.
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