Rates of neonatal death and cerebral palsy associated with fetal growth restriction among very low birthweight infants. A temporal analysis

Objective To assess whether changes over time in neonatal survival and infants' neurodevelopmental outcome among very low birthweight (VLBW) infants was correlated with the obstetric aetiology of VLBW. Design A cohort study of 773 VLBW infants. Setting A University hospital in Northern Italy. Population All the VLBW infants born over a 20-year period (1983-2002) at a single institution. Methods Evaluation of neonatal mortality and neurodevelopmental outcome of the surviving infants at 2 years of corrected age. Logistic regression analysis was used to compare the improvements of neonatal outcome associated with obstetric risk factors over time. Main outcome measures The risk reduction of neonatal death or cerebral palsy associated with each obstetric category responsible for VLBW over time. Results The overall rates of neonatal mortality and cerebral palsy were 38.7% (43/111) and 17% (9/53) in the period 1983-87 and 13.7% (34/24) and 6.3% (13/205) in the period 1998-2002, respectively. The adjusted decrement per 5-year period was 33.1% (95% CI=7.9-51.4) for neonatal death and 29.1% (95% CI=25.3-32.7) for cerebral palsy, respectively. The adjusted rise in the rate of intact survival at 2 years of corrected age was 7.6% (95% CI=3.1-12.3) per quinquennium. In logistic models with neonatal death or cerebral palsy as a combined outcome variable, and gestational age, corticosteroid use, surfactant use, and time of birth as explanatory variables, fetal growth restriction (P<0.001) and pre-eclampsia (P=0.011) interacted significantly with period of birth. The adjusted decrement in the rate of neonatal death or cerebral palsy as a combined variable was 27.5% per 5 years (95% CI=13-39.6) in the overall population, 54.5% per 5 years (95% CI=46.8-61.2) (P<0.001 compared with overall population) among growth-restricted infants and 50.3% per 5 years (95% CI=42.5-57.1) (P=0.003 compared with overall population) in infants born to mothers with pre-eclampsia. Conclusions Over a period of 20 years, the decrement in the rate of neonatal death or cerebral palsy was higher in growth-restricted fetuses than in other VLBW infants. This reduction was not obtained at the expense of an increased rate of neurodevelopmental impairments in surviving infants.