Stillbirth as a Risk Marker for Postpartum Readmission for Cardiovascular Disease: A Population-Based Retrospective Cohort Study.

BACKGROUND: Cardiovascular disease (CVD) remains a leading cause of pregnancy-related morbidity and death in the early postpartum period. Stillbirth is associated with elevated long-term CVD risk. However, whether stillbirth unmasks short-term CVD is less well characterized. METHODS: We conducted a population-based retrospective cohort study of singleton delivery hospitalizations using the Nationwide Readmissions Database (2010-2020). The primary outcome was CVD-related readmission or in-hospital death within the calendar year of delivery, including heart disease and stroke. Associations were estimated using adjusted Cox proportional hazards models and corrected for unmeasured confounding. Analyses were stratified by chronic hypertension, ischemic placental disease, and diabetes. RESULTS: Among 18 253 997 singleton delivery hospitalizations, 117 230 (6.5 per 1000) resulted in stillbirth. Median follow-up was 6.4 months (interquartile range, 3.7-9.1). The rate of CVD-related readmission was higher following stillbirth than live birth (404.0 versus 166.0 per 100 000 delivery hospitalizations; incidence proportion difference, 238 per 100 000 [95% CI, 192-285]). Stillbirth was associated with higher hazards of CVD hospitalization (adjusted hazard ratio [HR], 2.03 [95% CI, 1.78-2.32]), including heart disease (adjusted HR, 2.00 [95% CI, 1.72-2.32]), stroke (adjusted HR, 2.29 [95% CI, 1.80-2.92]), and CVD-related death (adjusted HR, 2.08 [95% CI, 1.12-3.84]). CVD hospitalization risk was elevated within 30 days postpartum and peaked from 60 to 89 days. Risks of CVD hospitalization were higher with co-occurring chronic hypertension, ischemic placental disease, or diabetes. CONCLUSIONS: Stillbirth was associated with increased short-term CVD-related readmission and death, extending prior evidence linking stillbirth to long-term CVD risk.