In 2012, the American College of Obstetricians and Gynecologists recommended a 30- to 60-second delay before clamping the umbilical cord in all preterm deliveries in order to ensure that at-risk newborns received the highest possible flow of blood from their cords. However, recent research has suggested that for preterm infants born by C-section, a technique known as cord "milking" may be even more efficient at increasing umbilical cord blood flow.

Cord milking consists of encircling the cord with the thumb and forefinger and gently squeezing in order to push the blood to the infant's abdomen. In a study published in the journal Pediatrics, researchers investigated the effectiveness of cord milking in preterm deliveries. According to the press release, the researchers studied 197 infants whose mothers had gone into labor at or before the 32nd week of pregnancy. Of these infants, a total of 154 were delivered by C-section. Of this group, 75 were randomly assigned to have their umbilical cord milked, while 79 were assigned to undergo delayed clamping. The 43 infants born vaginally were also randomly assigned to either have their cords milked or undergo delayed cutting.

Results showed that infants who underwent cord milking had higher blood flow in the vena cava, the vein that carries blood from the brain to the heart. This group also had a higher output of blood from the heart’s right ventricle and an overall higher blood pressure and levels of hemoglobin when compared to the delayed cutting group. These results suggest that the cord milking increases the flow of blood from the umbilical cord into the circulatory system and improves blood pressure and red blood cell levels.

“The study results are very encouraging,” said Dr. Tonse Raju, chief of NICHD’s Pregnancy and Perinatology Branch, as reported in the press 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.”

Premature infants are often at increased risk for a number of health concerns. Due to their early birth, researchers hypothesize preterm babies do not have as much blood in their bodies as full term infants. This decreased volume of blood may put them at greater risk for intraventricular hemorrhage (bleeding in the brain). In the most severe cases, bleeding in the brain may result in developmental delays, cerebral palsy, and even death.

Cord milking did not prove to be equally beneficial for preterm babies born vaginally. Results showed there were no significant differences in the blood volume or blood pressure between delayed cutting and cord milking among the small number of natural births.

Source: Katheria AC, Truoung G, Cousins L, Oshiro B, Finer NN. Umbilical Cord Milking Versus Delayed Cord Clamping in Preterm Infants. Pediatrics. 2015.