Epidemiologic study of neonatal jaundice. A survey of contributing factors.

In the attempt to detect factors influencing bilirubinemia in healthy full-term or near-term newborn infants, a statistical analysis was carried out on a population of 1,126 neonates to study the variables possibly associated with maximum bilirubin values reached in the first days of life. The following variables were studied: maximum bilirubin level (maxBIL), sex, mode of delivery, gestational age, birthweight, ratio of birthweight/weight on 5th day, Apgar score, Rh and ABO incompatibility. Blood glucose and calcium levels, haematocrit, intake of breast milk, formula and glucose solution were also evaluated during the first 5 days of life. Higher maxBIL was found in males compared to females, after spontaneous delivery vs. emergency caesarean section, after caesarean section without fetal distress vs. emergency caesarean section, and in ABO incompatibility vs. no ABO incompatibility. Statistically significant inverse correlations were observed between maxBIL and gestational age, birth weight, blood glucose, and SE-calcium. Significant positive correlations were found between maxBIL and haematocrit and breast milk intake. A multiple regression analysis between maxBIL and the significantly correlated parameters showed that only gestational age and birth weight remained significantly correlated with maxBIL. The results of the present investigation confirm that the factors most commonly reported as being responsible for neonatal hyperbilirubinemia do in fact play a role, although it can be considered almost negligible with the exception of gender, mode of delivery, ABO incompatibility, birthweight and gestational age.