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 ( E nc‐ CP ). Methods A retrospective review of 132 singleton infants with E nc‐ 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 J anuary 2009 in J apan; no identifiable causes of cerebral palsy other than antenatal or intrapartum hypoxia; and exhibition of neonatal encephalopathy. National statistics of J apan 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 E nc‐ 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 E nc‐ CP .