Is breastfeeding really favoring early neonatal jaundice?

Objective. The purpose of this study was to evaluate the development of sig nificant hyperbilirubinemia in a large unselected newborn population in a m etropolitan area with particular attention to the relationship between type of feeding and incidence of neonatal jaundice in the first week of life. Study Design. A population of 2174 infants with gestational age greater tha n or equal to 37 weeks was prospectively investigated during the first days of life. Total serum bilirubin determinations were performed on infants wi th jaundice. The following variables were studied: type of feeding, method of delivery, weight loss after birth in relationship to the type of feeding , and maternal and neonatal risk factors for jaundice. Statistical analyses were performed using the z test for parametric variables and the t test fo r nonparametric variables. In addition, the multiple logistic regression al lows for the estimation of the role of the individual characteristics in th e development of hyperbilirubinemia. Data concerning serum bilirubin peak d istribution in jaundiced newborns were analyzed using a single and a double Gaussian best fit at least squares. The t test was performed to compare 2 values (high and low) of the serum bilirubin peak in breastfed and suppleme ntary-fed infants with those in bottle-fed infants. Results. The maximal serum bilirubin concentration exceeded 12.9 mg/dL (221 mmol/L) in 112 infants (5.1%). The study demonstrated a statistically sign ificant positive correlation between patients with a total serum bilirubin concentration >12.9 mg/dL (221 mmol/L) and supplementary feeding; oppositel y, breastfed neonates did not present a higher frequency of significant hyp erbilirubinemia in the first days of life. However, best Gaussian fitting o f our data suggests that a small subpopulation of breastfed infants have a higher serum bilirubin peak than do bottle-fed infants. Newborns with significant hyperbilirubinemia underwent a greater weight los s after birth compared with the overall studied population, and infants giv en mixed feeding lost more weight than breastfed and formula-fed newborns, indicating that formula has been administered in neonates who had a weight loss beyond a predetermined percentage of birth weight. Significant hyperbi lirubinemia was also strongly associated with delivery by vacuum extractor, some perinatal complications (cephalohematoma, positive Coombs' test, and blood group systems of A, AB, B, and O [ABO] incompatibility) and Asian ori gin. Multiple logistic regression analysis shows that supplementary feeding , weight loss percentage, ABO incompatibility, and vacuum extraction signif icantly increase the risk of jaundice, while only cesarean section decrease s the risk. Conclusion. The present study confirms the important role of fasting in the pathogenesis of neonatal hyperbilirubinemia, although breastfeeding per se does not seem related to the increased frequency of neonatal jaundice but to the higher bilirubin level in a very small subpopulation of infants with jaundice. In fact, in the breastfed infants, there is a small subpopulatio n with higher serum bilirubin levels. These infants, when starved and/or de hydrated, could probably be at high risk of bilirubin encephalopathy.