A previous study suggested that umbilical cord milking, a technique that moves blood from the umbilical cord into a newborn’s body, reduced the need for heart and respiratory support among infants classified as nonvigorous—limp, pale, and with minimal breathing—compared to the standard intervention, immediate cord clamping and cutting. A follow-up study supported by the National Institutes of Health indicates that the benefits of the technique may result from increased blood flow to the lungs and brain, along with an increase in blood pumped from the heart. The findings offer additional support for the use of umbilical cord milking in nonvigorous near term and term infants.
The study was conducted by Anup Katheria, M.D., of the Sharp Mary Birch Hospital for Women and Newborns, and colleagues. It appears in The Journal of Pediatrics. Funding was provided by NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development.
Background
Previous studies have shown that when compared to the traditional practice of immediate cord clamping and cutting, delaying cord clamping for healthy term infants for at least 30 to 60 seconds allows blood from the umbilical cord to enter the infant’s circulation. Compared to healthy infants who underwent immediate cord clamping and cutting, those undergoing delayed cord clamping had higher iron levels and better long-term neurological development.
Nonvigorous infants are at risk for complications such as low brain oxygen levels, cerebral palsy, and stroke. The standard practice for these infants was to immediately clamp and cut the cord so the infant could be resuscitated.
In a previous study of 1,730 nonvigorous infants born between 35 to 42 weeks of pregnancy, the authors compared cord milking to immediate clamping. Providers milked 20 centimeters of cord for two seconds, repeating this procedure three times. Compared to nonvigorous infants undergoing cord clamping, those who underwent cord milking were less likely to need heart and respiratory support, less likely to have a low level of oxygen in the brain, and more likely to have higher levels of hemoglobin, a substance indicating the presence of red blood cells.
For the current study, researchers conducted echocardiograms of 227 infants from the original study, 6 to 18 hours after delivery, to determine the safety of cord milking.
Results
Compared to infants who underwent immediate clamping, those who underwent cord milking had a larger volume of blood pumped from the heart’s left ventricle, which sends blood throughout the body. Similarly, they had a higher volume of blood flowing to the heart from the superior vena cava, the large vein which feeds blood to the heart from the upper limbs, head, and neck. They also had a higher volume of blood from the right ventricle, the heart chamber that pumps oxygen-depleted blood to the lungs.
Significance
The increased circulation the authors observed in the infants undergoing cord milking may explain why infants who underwent the procedure were less likely to need heart and respiratory support or to have a low brain oxygen level. The authors noted that in many nonvigorous infants, compression of the umbilical cord during labor may cause a large volume of blood to be transferred from the infant to the placenta. Cord milking, they theorized, may return much of this blood back to the infant. The authors concluded that their findings support the use of umbilical cord milking in nonvigorous term and near-term infants.
Reference
Katheria, A. et al. Hemodynamic changes with umbilical cord milking in nonvigorous newborns: a randomized cluster cross-over trial. The Journal of Pediatrics. 2022. https://doi.org/10.1016/j.jpeds.2023.03.001 
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