Prepregnancy Emergency Department Use and Risks of Severe Maternal and Neonatal Morbidity in Canada.

Importance: Emergency department (ED) use during pregnancy may be associated with worse obstetrical outcomes, possibly because of differences in access to health care. It is not known whether ED use before pregnancy is associated with serious adverse maternal and perinatal outcomes. Objective: To study the association between prepregnancy ED use and adverse maternal and perinatal outcomes. Design, Setting, and Participants: This population-based cohort study was conducted in Ontario, Canada, and included all livebirths and stillbirths from April 2003 to January 2020. Exposures: Main exposure was any ED encounter within 90 days preceding the start of the index pregnancy. Main Outcomes and Measures: Primary outcome was a composite of severe maternal morbidity (SMM) from 20 weeks' gestation to 42 days' post partum. Secondary outcomes included severe neonatal morbidity (SNM) from 0 to 27 days, neonatal death, and stillbirth. Relative risks (RRs) were adjusted for maternal age, income, and rurality. Results: Of 2 130 245 births, there were 2 119 335 livebirths (99.5%) and 10 910 stillbirths (0.5%). The mean (SD) maternal age was 29.6 (5.4) years, 212 478 (9.9%) were rural dwelling, and 498 219 (23%) had 3 or more comorbidities. Among all births, 218 011 (9.7%) had a prepregnancy ED visit. The rate of SMM was higher among women with a prepregnancy ED visit than those without (22.3 vs 16.5 per 1000 births), with an RR of 1.34 (95% CI, 1.30-1.38) and an adjusted RR (aRR) of 1.37 (95% CI, 1.33-1.42). Compared with no prepregnancy ED visit, the aRR was higher in those with 1 (1.29; 95% CI, 1.24-1.34), 2 (1.51; 95% CI, 1.42-1.61), and 3 or more (1.74; 95% CI, 1.61-1.90) ED visits. Prepregnancy ED visits for a hematological (aRR, 13.60; 95% CI, 10.48-17.64), endocrine (aRR, 4.96; 95% CI, 3.72-6.62), and circulatory (aRR, 2.27; 95% CI, 1.68-3.07) conditions were associated with the highest aRRs for SMM. The rate of SNM was higher among newborns whose mother visited the ED within 90 days before pregnancy (68.2 vs 55.4 per 1000 births; aRR, 1.24; 95% CI, 1.22-1.26) as was the risk of neonatal death (aRR, 1.26; 95% CI, 1.16-1.37) and stillbirth (aRR, 1.18; 95% CI, 1.11-1.25). Conclusions and Relevance: In this study, ED use was common before pregnancy. These findings suggest that ED use may not only reflect a woman's access to prepregnancy care but also higher future risk of severe maternal and perinatal morbidity, potentially offering a useful trigger for health system interventions to decrease adverse pregnancy outcomes.