Losing more than 10% of birthweight early in the postnatal course is common among neonates delivered vaginally and by cesarean section who have been exclusively breastfed, nomograms developed by a team of researchers show. Those graphical depictions of hourly weight loss “may inform clinical care,” Dr. Valerie J. Flaherman and her colleagues reported in Pediatrics.
“The availability of detailed data on weight and feeding for a large cohort allows this study to present the first graphical depiction of hourly weight loss for exclusively breastfed newborns from a large, diverse population,” wrote Dr. Flaherman of the University of California, San Francisco, and her colleagues. “Our curves demonstrate that expected weight loss differs substantially by method of delivery and that this difference persists over time” (Pediatrics 2014 Dec. 1 [doi:10.1542/peds.2014-1532]).
Using available weight data from the births of 108,907 singleton neonates born at 36 weeks’ gestation or later at Northern California Kaiser Permanente hospitals between 2009 and 2013, the researchers created nomograms that estimate percentiles of weight loss among exclusively breastfed infants who were vaginally delivery or delivered by cesarean section.
Dr. Flaherman’s team estimated 50th, 75th, 90th, and 95th percentiles based on analysis of 83,433 vaginally born neonates and 25,474 infants delivered by C-section, all exclusively breastfed. The study excluded infants who received any formula, those weighing less than 2,000 g or more than 5,000 g, and those whose weight, delivery mode, or feeding status was unknown.
Median weight loss for vaginally delivered newborns was 4.2%, 7.1%, and 6.4% at 24, 48, and 72 hours after birth, respectively. Among cesarean section–born newborns, median percent weight loss was 4.9%, 8%, 8.6%, and 5.8% at 24, 48, 72, and 96 hours after birth.
Nearly 5% of vaginally delivered newborns and nearly 10% of newborns delivered by cesarean section had lost at least 10% of their birthweight at 48 hours after birth. Percentile curves began to rise shortly after 48 hours for vaginally delivered newborns and by 72 hours after birth for cesarean section–delivered newborns, although more than 25% of the latter remained at least 10% below their birthweight by the third day.
The research was funded by the U.S. Department of Health & Human Services and the National Institute of Child Health and Human Development. The authors reported no disclosures.