Comorbidities and Complications: How the Association of Caesarean Delivery With Postpartum Hospital Encounters Varies by Risk Indicator

BACKGROUND: Objective: Research on potentially avoidable caesarean deliveries frequently centres on births to nulliparous birthing people with a singleton, term delivery with vertex presentation (NTSV). However, caesarean deliveries in this population are heterogeneous, and little is known about how the association with caesarean delivery varies across risk indicators. We aimed to estimate absolute associations between caesarean delivery, categorised by risk indicators, and postpartum hospital encounters within 1 year among NTSV birthing people in Massachusetts. METHODS: We used data from the Pregnancy and Early Life Longitudinal data system, which captures birth certificate and hospital discharge data for all births in Massachusetts from 2011 to 2019. Risk indicators were categorised into five groups: chronic/acute disease, placental complications, labour complications, fetal concerns and no documented risk. We estimated risk differences for the association of caesarean versus vaginal delivery with hospital encounters within one year postpartum according to risk indication subgroup. Hospital encounters within 30 days, 31 to 180 days and 181 to 365 days were examined. RESULTS: Overall, we estimated 23 (95% confidence interval [CI] 19, 27) excess cases of one-year postpartum hospital encounters per 1000 live births for caesarean deliveries compared to vaginal deliveries. Among birthing people with no documented risk, caesarean delivery was not associated with higher postpartum hospital encounter rates within one year compared to vaginal deliveries. Caesarean delivery was associated with an increased risk of hospital encounters for all other subgroups. All estimated risk differences were positive for hospital encounters within 30 days; however, across all subgroups, these associations diminished after 180 days postpartum. CONCLUSIONS: The association of caesarean delivery with postpartum hospital encounters varies by risk indicator and by the timing of the postpartum hospital encounter. These results suggest that caesarean deliveries among those with no documented risk are not associated with an increased risk of postpartum hospital encounter.