Risk of cerebral palsy associated with neonatal encephalopathy in macrosomic neonates.

AIM: To determine whether macrosomic infants with a birthweight of 4.0 kg or more have increased risk of cerebral palsy associated with neonatal encephalopathy (Enc-CP). METHODS: A retrospective review of 132 singleton infants with Enc-CP fulfilling all of the following criteria: born at gestational week (GW) 37 or more (n = 126) or weighing 2.5 kg or more at birth (n = 116) in or after January 2009 in Japan; no identifiable causes of cerebral palsy other than antenatal or intrapartum hypoxia; and exhibition of neonatal encephalopathy. National statistics of Japan were used to determine the numbers of infants according to birthweight categories. RESULTS: Of the 116 infants with a birthweight of 2.5 kg or more, 46 (39.7%), 49 (42.2%), 17 (14.7%) and four (3.4%) infants had birthweights of 2.5-2.99, 3.0-3.49, 3.5-3.99 and 4.0 kg or more, respectively. Corresponding figures among Japanese infants born in 2009-2011 were 42.8%, 45.4%, 10.9% and 0.90%, respectively. Infants with a birthweight of 4.0 kg or more had a relative risk (95% confidence interval) of Enc-CP of 3.89 (1.52-9.95) compared to those with a birthweight of 2.5-2.99 kg. CONCLUSION: Japanese infants with a birthweight of 4.0 kg or more have increased risk of Enc-CP.