Objective: To estimate the effect of maternal age on survival free of major morbidity among preterm newborns younger than 33 weeks of gestation at birth.
Methods: Data from a retrospective cohort of preterm newborns younger than 33 weeks of gestation admitted to Canadian neonatal intensive care units between 2003 and 2008 were analyzed. The primary outcome was survival without major morbidity (defined as bronchopulmonary dysplasia, intraventricular hemorrhage grade 3 or 4, periventricular leukomalacia, retinopathy of prematurity stage 3, 4 or 5, or necrotizing enterocolitis stage 2 or 3). Trends in outcomes in relation to maternal age groups were examined using a multivariable analysis that controlled for confounders.
Results: Baseline comparison for the 12,326 eligible newborns revealed no differences in sex, small-for-gestational-age status, and chorioamnionitis among different maternal age groups. Higher rates of cesarean delivery, use of prenatal steroids, maternal hypertension, and diabetes were noted as maternal age increased (P<.01). Increasing maternal age was associated with increased survival without major morbidity (adjusted odds ratio [OR] 1.047, 95% confidence interval [CI] 1.001-1.095) and reductions in mortality (adjusted OR 0.922, 95% CI 0.855-0.955), necrotizing enterocolitis (adjusted OR 0.888, 95% CI 0.816-0.967), and sepsis (adjusted OR 0.904, 95% CI 0.862-0.948).
Conclusion: Among preterm newborns, the odds of survival without major morbidity improved by 5% and mortality (8%), necrotizing enterocolitis (11%), and sepsis (9%) reduced as maternal age group increased by 5 years.
Level of evidence: II.