Pregnancy disorders leading to very preterm birth influence neonatal outcomes: results of the population-based ACTION cohort study

BACKGROUND: We examined the relationships between pregnancy disorders leading to very preterm birth (spontaneous preterm labor, prelabor premature rupture of membranes (PPROM), hypertension/preeclampsia, intrauterine growth restriction (IUGR), antenatal hemorrhage, and maternal infection), both in isolation and grouped together as "disorders of placentation" (hypertensive disorders and IUGR) vs. "presumed infection/inflammation" (all the others), and several unfavorable neonatal outcomes. METHODS: We examined a population-based prospective cohort of 2,085 singleton infants of 23-31 wk gestational age (GA) born in six Italian regions (the Accesso alle Cure e Terapie Intensive Ostetriche e Neonatali (ACTION) study). RESULTS: Neonates born following disorders of placentation had a higher GA and better overall outcomes than those born following infection/inflammation. After adjustment for GA, however, they showed higher risk of mortality (odds ratio, OR: 1.4; 95% confidence interval, CI: 1.0-2.0), bronchopulmonary dysplasia (BPD) (OR: 2.5; Cl: 1.8-3.6), and retinopathy of prematurity (ROP) (OR: 2.0; Cl: 1.1-3.5), especially in growth-restricted infants, and a lower risk of intraventricular hemorrhage (IVH) (OR: 0.5; Cl: 0.3-0.8) and periventricular leukomalacia (PVL) (OR: 0.6; CI: 0.4-1.1) as compared with infants born following infection/inflammation disorders. CONCLUSION: Our data confirm the hypothesis that, in very preterm infants, adverse outcomes are both a function of immaturity (low GA) and of complications leading to preterm birth. The profile of risk is different in different pregnancy disorders.