Predicting Nonhemolytic Neonatal Hyperbilirubinemia

BACKGROUND: Before hospital discharge, newborn infants should be assessed for the risk of excessive hyperbilirubinemia. We determined maternal and obstetric risk factors for hyperbilirubinemia in infants born at term (gestational age >= 37 weeks) to form an individualized risk assessment tool for clinical use. METHODS: This was a population-based study with data from the Swedish Medical Birth Register from 1999 to 2012, including 1 261 948 singleton infants. Outcome was defined as infants diagnosed with hyperbilirubinemia (N = 23 711), excluding all cases of hemolytic (immunemediated or other specified hemolytic) diseases of the newborn. RESULTS: Risk factors with an adjusted odds ratio (aOR) for neonatal hyperbilirubinemia of >= 1.5 (medium-sized effect or more) were gestational age 37 to 38 weeks (aOR = 2.83), failed vacuum extraction (aOR = 2.79), vacuum extraction (aOR = 2.22), Asian mother (aOR = 2.09), primipara (aOR = 2.06), large-for-gestational-age infant (aOR = 1.84), obese mother (aOR = 1.83), and small-for-gestational-age infant (aOR = 1.66). Planned cesarean delivery (CD) was associated with a reduced risk (aOR = 0.45). Without any of these risk factors (normal birth weight infant delivered vaginally at 39 to 41 weeks' gestation by a non-Asian, nonobese, multiparous mother) the rate of nonhemolytic neonatal hyperbilirubinemia was 0.7%. In relation to the combined load of different risk factors, rates of neonatal hyperbilirubinemia ranged from 0.2% to 25%. CONCLUSIONS: Collection of a few easily available maternal and obstetric risk factors predicts >100-fold variation in the incidence of neonatal hyperbilirubinemia. The information provided herein enables individualized risk prediction with interactions between different risk factors taken into account.