Risk of Adverse Neonatal Events in Pregnancies Complicated by Severe Maternal Morbidity

Objective To investigate the risk of adverse neonatal events after a pregnancy complicated by severe maternal morbidity. Study design We analyzed a population-based cohort of deliveries in Quebec, Canada, from between 2006 and 2021. The main exposure measure was severe maternal morbidity comprising life-threatening conditions, such as severe hemorrhage, cardiac complications, and eclampsia. The outcome included adverse neonatal events, such as very preterm birth (gestational age <32 weeks), bronchopulmonary dysplasia, hypoxic ischemic encephalopathy, and neonatal death. Using log-binomial regression models, we estimated adjusted relative risks (RR) and 95% confidence intervals (CI) for the association between severe maternal morbidity and adverse neonatal events. Results Among 1,199,112 deliveries, 29,992 (2.5%) were complicated by severe maternal morbidity and 83,367 (7.0%) had adverse neonatal events. Severe maternal morbidity was associated with 2.96 times the risk of adverse neonatal events compared with no morbidity (95% CI 2.90-3.03). Associations were greatest for mothers who required assisted ventilation (RR 5.86, 95% CI 5.34-6.44), experienced uterine rupture (RR 4.54, 95% CI 3.73-5.51), or had cardiac complications (RR 4.39, 95% CI 3.98-4.84). Severe maternal morbidity was associated with ≥3 times the risk of neonatal death and hypoxic-ischemic encephalopathy and ≥10 times the risk of very preterm birth and bronchopulmonary dysplasia. Conclusions Severe maternal morbidity is associated with an elevated risk of adverse neonatal events. Better prevention of severe maternal morbidity may help reduce burden of severe neonatal morbidity.