Post-term pregnancy is an independent risk factor for neonatal morbidity even in low-risk singleton pregnancies

Objective To determine the independent association of post-term pregnancy with neonatal outcome in low-risk newborns. Design Retrospective cohort. Setting Tertiary university-affiliated medical centre. Patients All newborns of low-risk singleton pregnancies born at 39+0 to 44+0 weeks’ gestation over a 5-year period. Exclusion criteria: multiple gestation, maternal hypertensive disorder, diabetes or cholestasis, placental abruption or intrapartum fever (>38°C), small for gestational age ( Interventions None. Outcome measures Admission to the neonatal intensive care unit (NICU), hospital length of stay, 5-min Apgar score, birth trauma, respiratory, neurological, metabolic and infectious morbidities and neonatal mortality. The adverse outcome rate was compared among three groups based on gestational age at birth: post-term (≥42+0 weeks), late term (41+0 to 41+6 weeks) and full term (39+0 to 40+6 weeks). Results Of the 23 524 eligible neonates, 747 (3.2%) were born post-term, 4632 (19.7%) late term and 18 145 (77.1%) full term. Women in the post-term group versus the late-term group had a significantly higher rate of caesarean section (8.9% vs 5.6%, p Conclusions Post-term pregnancy is an independent risk factor for neonatal morbidity even in low-risk singleton pregnancies.