Objective: To identify pregnancies at risk for adverse outcomes in the late preterm (LP) period, we investigated how gestational age (GA) at delivery, circumstances at parturition, and specific prenatal risk factors may affect neonatal outcomes. Study design: Prospective, area-based cohort study of neonatal morbidity and mortality among singleton infants born between 34+0 and 36+6 weeks, at 21 L&D units in Emilia Romagna county, Italy, during 2013-15. The primary neonatal outcome was a composite of Apgar 5’ ≤ 3, umbilical-cord-blood arterial pH < 7.0, RDS, TTN, hypoglycemia, sepsis, confirmed seizures, stroke, IVH, cardiopulmonary resuscitation, invasive respiratory support and hospitalization ≥ 5 days. Multivariate logistic regression models were used to respectively investigate the effects on study outcomes of 1) GA at delivery and circumstances at parturition 2) GA at delivery and prenatal risk factors, after controlling for confounding Results: Among 1867 births, 302, 504 and 1061 infants were born at 34, 35 and 36 weeks, respectively. There were no neonatal deaths. When studying circumstances at parturition, an increased risk of composite neonatal outcome was observed among 34 weeks births, 35 weeks deliveries, and indicated deliveries. When studying prenatal risk factors, neonatal morbidity was associated with delivery 34 weeks, birth at 35 weeks, pregestational diabetes, pPROM, maternal BMI, bleeding and polyhidramnios; instead, preeclampsia had a protective effect. Conclusion: LP with indicated deliveries at 34 or 35 weeks, or with specific prenatal risk factors have worse neonatal outcome when compared to 36. Such differences should be considered when counseling patients and planning interventions.
