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.