Abstract 13354: Higher Severe Maternal Morbidity Rates at Delivery Hospitalization Among Racial and Ethnic Groups Related to Chronic Hypertension and Hypertensive Disorders of Pregnancy

Abstract

Severe maternal morbidity (SMM) affects 0.5-3% of pregnancies in the United States, with risk varying for racial and ethnic groups. Studies have rarely evaluated how chronic hypertension (cHTN) and hypertensive disorders of pregnancy (HDP) affect differences in SMM risk. This study sought to evaluate cHTN and HDP as contributors to racial disparities in SMM rates. Retrospective cohort study of 263,518 patients aged 18-46 years who received prenatal care ≤14 weeks' gestation and delivered a stillborn or live singleton birth ≥20 weeks’ gestation at a Kaiser Permanente Northern California hospital (2009-2019). We evaluated the relation of cHTN and HDP [preeclampsia (PE), gestational hypertension (GH) and superimposed preeclampsia (s_PE)] to SMM at delivery hospitalization, defined as the presence of at least 1 of 21 conditions meeting CDC criteria. Modified Poisson regression models estimated the adjusted relative risk (aRR) of SMM associated with cHTN and HDP among self-reported racial and ethnic groups [Asian, Black, Hispanic, Native Hawaiian Pacific Islander (NHPI), White] adjusted for covariables. There were 13,626 women (5.2%) with cHTN, in whom 4297 (31.5%) developed s_PE. For patients with no cHTN, 11,744 (4.7%) developed PE and 11,514 (4.6%) developed GH. The overall SMM rate (number of cases/10,000 births) was 219.7. SMM rates were higher for patients with cHTN vs no cHTN (417.6 vs. 208.9, p<.0001), and for PE (934.3) and s_PE (898.3) vs no cHTN + no HDP (165.9), p<0.001. SMM rates differed for racial and ethnic groups. Compared to White patients with No cHTN or HDP, aRRs of SMM associated with PE and s_PE increased in order for White, Asian, Hispanic, Black, and NHPI groups (Table 1). Preeclampsia was 6 times more prevalent among those with cHTN than no cHTN. Preeclampsia was strongly associated with higher SMM rates in both women with cHTN and without cHTN, especially among NHPI and Black groups. Preeclampsia may contribute substantially to racial disparities in SMM.