The Impact of Severe Maternal Morbidity on Very Preterm Infant Outcomes

Severe maternal morbidity is defined as a life-threatening diagnosis or lifesaving procedure during delivery. It occurs more often in very preterm deliveries, as opposed to term deliveries. There has been significant research on the impact of severe maternal morbidity on maternal outcomes, but there has been little research on how it can affect very preterm infants. The goal of this study was to determine the prevalence of severe maternal morbidity among very preterm births before 32 weeks' gestation and to determine the risk factors associated with very preterm infant mortality and morbidity. This study used New York City Vital Statistics birth and death records linked with maternal and newborn discharge abstract data in New York State for all live births between 2010 and 2014. This amounted to 6901 infants born between 24 and 32 weeks' gestation to 6138 mothers. Births at less than 24 weeks' gestational age and those with congenital anomalies were excluded. The outcomes measured were first-year infant mortality, severe neonatal morbidity, and a combined outcome of death or morbidity. First-year infant mortality encompassed deaths in-hospital and after being discharged. Severe neonatal morbidity was defined as bronchopulmonary dysplasia, necrotizing enterocolitis, stages 3 to 5 of retinopathy of prematurity, and intraventricular hemorrhage grades 3 to 4. In this study cohort, 843 of 6901 infants (approximately 12%) had a mother with a severe maternal morbidity. Maternal characteristics associated with a higher risk of severe maternal morbidity included being older, multiparous, and non-Hispanic black, as well as having preexisting health conditions. Interestingly, gestational age at delivery and percentage of small-for-gestational-age infants were not associated with severe maternal morbidity. Cases with severe maternal morbidity yielded more cesarean deliveries. After adjusting for maternal characteristics, preexisting comorbidities, pregnancy complications, and hospital components, infants whose mothers had severe maternal morbidity had a higher mortality rate in the first year of life (11.2% vs 7.7% in those without severe maternal morbidity). This generated a relative risk of 1.39 (95% confidence interval, 1.14-1.70). Of note, severe maternal morbidity was not associated with neonatal morbidity. Overall, the 12% of mothers who had very preterm live births and severe maternal morbidity were associated with a 39% increased risk of infant death after adjusting for sociodemographic and clinical factors. There are various possible explanations for this association, raising the possibility that quality initiatives focused on severe maternal morbidity could lead to a reduction in infant mortality. In the future, more data should be collected on maternal outcomes in relation to very preterm infants.