Severe maternal morbidity and hypertensive disorders of pregnancy among women with intellectual disabilities: Identifying potential intervention targets.

BACKGROUND: Women with intellectual disabilities have a higher prevalence of chronic health conditions and behavioral risk factors, yet the extent to which these factors contribute to adverse maternal outcomes is unclear.

OBJECTIVE: To identify and prioritize intervention targets to reduce severe maternal morbidity and hypertensive disorders of pregnancy among women with intellectual disabilities.

STUDY DESIGN: We conducted a population-based cohort study linking 2007-2020 California birth and fetal death records with hospital discharge, emergency department, and ambulatory surgery data. Among 6,099,797 singleton births, including 1114 women with intellectual disabilities, we created a 1:30 matched cohort of women with and without intellectual disabilities, matched on age, birth year, race/ethnicity, payer type, participation in the Supplemental Nutrition Program for Women, Infants, and Children, and maternal nativity. Intellectual disability and outcomes were identified from International Classification of Diseases codes at delivery. We used generalized linear modeling to estimate risk differences, risk ratios, and respective 95% confidence intervals for the association between intellectual disabilities and adverse maternal outcomes including severe maternal morbidity, preeclampsia, and gestational hypertension. We performed regression-based joint and single mediation analyses to assess the contribution of selected mediators to the association between intellectual disabilities and these adverse maternal outcomes.

RESULTS: Women with intellectual disabilities were younger [26.8 (SD=5.9) vs 29.0 (SD=6.2) years] and more likely to be non-Hispanic Black (19% vs 5%), have public payer for delivery (82% vs 48%), participate in nutrition assistance (79% vs 50%), and be born in the US (92% vs 80%). In the adjusted matched analytic sample, women with intellectual disabilities (n=1107) were more likely to have inadequate prenatal care (40% vs 29%), substance use disorders during pregnancy (11%-16% vs 3%-6%) and mental health conditions (12%-16% vs 2%) compared to women without intellectual disabilities (n=33,174). Additionally, they were more likely to have chronic comorbidities including respiratory conditions (19% vs 6%), epilepsy (12% vs 1%), preexisting hypertension (7% vs 3%), preexisting diabetes (7% vs 1%), or hyperthyroidism or hypothyroidism (4% vs 1%). Compared to those without intellectual disabilities, women with intellectual disabilities had an adjusted excess risk per 100 deliveries was 3.0 for severe maternal morbidity (95% CI: 1.8, 4.4), 7.8 for preeclampsia (95% CI: 5.8, 9.7), and 6.9 for gestational hypertension (95% CI: 4.8, 9.0). Corresponding adjusted risk ratio was 2.7 (95% CI: 2.1, 3.5) for severe maternal morbidity, 2.8 (95% CI: 2.3, 3.3) for preeclampsia, 2.0 (95% CI: 1.7, 2.3) for gestational hypertension. Jointly, all mediators with sufficient frequencies explained 29.1% (95% CI: 15.9, 50.3) of the association between intellectual disability and severe maternal morbidity, 37.6% (95% CI: 27.6, 52.0) for preeclampsia, and 25.4% (95% CI: 5.8, 47.8) for gestational hypertension. In single-mediator analyses, epilepsy accounted for the greatest proportion of the total effect for severe maternal morbidity (11%), preexisting hypertension was the strongest mediator for preeclampsia (16%), and anxiety showed the highest proportion mediated for gestational hypertension (21%).

CONCLUSIONS: Chronic comorbidities and behavioral risk factors accounted for roughly one-quarter to one-third of the increased risks of severe maternal morbidity and hypertensive disorders of pregnancy among women with intellectual disabilities. These findings highlight opportunities for targeted preconception and prenatal interventions to improve maternal health equity.