The Overlap of Maternal and Neonatal Critical Care Admission in the United States: Trends and Risk Factors in 2016-2024.

Background/Objectives: Maternal and neonatal intensive care unit (ICU) admissions are markers of severe perinatal morbidity, yet their co-occurrence within the same birth remains poorly characterized at the population level. The objective of this study was to examine temporal trends, distribution, and maternal risk factors associated with concurrent maternal and neonatal ICU admission among singleton births in the United States. Methods: This population-based, serial cross-sectional study used the US Centers for Disease Control and Prevention Wide-Ranging Online Data for Epidemiologic Research (WONDER) database from 2016 to 2024. Singleton live births were included and classified into four mutually exclusive ICU phenotypes: maternal ICU admission only, neonatal ICU admission only, concurrent maternal-neonatal ICU admission, and neither. Annual rates per 1000 births were calculated, and temporal trends were assessed using joinpoint regression. Maternal characteristics associated with concurrent ICU admission were evaluated using descriptive analyses and crude relative risks. Results: The analytic cohort included 32,341,764 singleton births. Between 2016 and 2024, rates of neonatal ICU admission increased from 76.35 to 88.46 per 1000 births (average annual percent change [AAPC], 1.65%; 95% CI, 1.35-1.92%) and maternal ICU admission from 1.49 to 1.82 per 1000 births (AAPC, 2.48%; 95% CI, 1.73-3.14%). Concurrent maternal-neonatal ICU admission remained uncommon but increased from 0.70 to 0.92 per 1000 births (AAPC, 3.32%; 95% CI, 1.67-4.88%). Across gestational age, neonatal ICU admission without maternal ICU admission was the dominant phenotype, particularly at earlier gestational ages. Concurrent ICU admission showed a similar but attenuated pattern, whereas maternal ICU admission without neonatal ICU admission remained uncommon, with relatively higher rates at the earliest gestational ages. Concurrent ICU admission was associated with markers of maternal and pregnancy risk. The highest risks were observed among pregnancies complicated by eclampsia, pre-pregnancy diabetes, and pre-pregnancy hypertension, as well as among women with no prenatal care. Risk increased with advancing maternal age and higher body mass index, and disparities were observed across racial groups. Conclusions: Concurrent maternal and neonatal ICU admission is a rare but increasing outcome concentrated among high-risk pregnancies. These findings highlight the need for integrated maternal-neonatal risk assessment and continued surveillance of severe perinatal outcomes.