A new technique used to increase the flow of blood from the umbilical cord to the circulatory system of premature infants delivered by cesarean appears offer greater benefits than delayed cord clamping, according to a new study.
According to an NIH news release, the technique, known as cord milking, is accomplished by encircling the cord with the thumb and forefingers, gently squeezing, and slowly pushing the blood through the cord into the infant’s abdomen. For infants delivered by C-section, cord milking offers more benefits – greater blood flow to and from the heart, a higher red blood cell level, and higher blood pressure – than the practice of waiting 45 seconds to 60 seconds before clamping and cutting the cord.
It has been thought delayed cord cutting allows sufficient time for blood from the umbilical cord to fill the blood vessels in infants’ lungs. Among premature infants, the delay is believed to protect against intraventricular hemorrhaging – bleeding into cavities inside the infant’s brain. This bleeding is thought to be caused by low blood pressure brought on by having too little blood in the circulatory system.
However, the study’s first author, Anup C. Katheria, MD, a neonatologist at the Neonatal Research Institute at the Sharp Mary Birch Hospital for Women and Newborns in San Diego, noted that some studies found that delayed cord clamping failed to reduce intraventricular hemorrhaging.
Katheria and his colleagues suspected that the use of anesthesia in C-sections reduces uterine contractions and in doing so, hinders the release of blood from the umbilical cord. The investigators theorized that cord milking might make up for the diminished blood flow through the umbilical cord and increase the amount of blood available to the infant.
To test their theory, the researchers followed 197 infants whose mothers went into labor at or before week 32 of their pregnancy. Of these, 154 were delivered by C-section, with 75 randomly assigned to the umbilical cord milking group and 79 assigned to the delayed clamping group. The remaining 43 infants were delivered vaginally and were also randomly assigned to either a cord milking or delayed cord clamping group.
The findings showed that among the infants delivered by cesarean, those who had cord milking showed a higher blood flow in the large vein carrying blood from the brain to the heart, and a higher output of blood from the right ventricle than the delayed cord clamping infants. When combined, these two measures are an indication of blood circulation in the brain and body.
In addition, infants in the cord milking group had higher blood pressure and higher levels of hemoglobin – a protein used as an indicator of the quantity of red blood cells. The researchers found there were no differences in blood volume among the two groups of infants delivered vaginally.
“The study results are very encouraging,” Tonse Raju, MD, chief of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Pregnancy and Perinatology Branch, said in the NIH news release. “The findings need to be confirmed in a larger number of births, but at this point, it appears that umbilical cord milking may prove to be of great benefit to preterm infants delivered via cesarean,” he added.
