Maternal Emergency Department Use Before Pregnancy and Infant Emergency Department Use After Birth.

Importance: Maternal emergency department (ED) use before or during pregnancy is associated with worse obstetrical outcomes, for reasons including preexisting medical conditions and challenges in accessing health care. It is not known whether maternal prepregnancy ED use is associated with higher use of the ED by their infant. Objective: To study the association between maternal prepregnancy ED use and risk of infant ED use in the first year of life. Design, Setting, and Participants: This population-based cohort study included all singleton livebirths in all of Ontario, Canada, from June 2003 to January 2020. Exposures: Any maternal ED encounter within 90 days preceding the start of the index pregnancy. Main Outcomes and Measures: Any infant ED visit up to 365 days after the index birth hospitalization discharge date. Relative risks (RR) and absolute risk differences (ARD) were adjusted for maternal age, income, rural residence, immigrant status, parity, having a primary care clinician, and number of prepregnancy comorbidities. Results: There were 2 088 111 singleton livebirths; the mean (SD) maternal age was 29.5 (5.4) years, 208 356 (10.0%) were rural dwelling, and 487 773 (23.4%) had 3 or more comorbidities. Among singleton livebirths, 206 539 mothers (9.9%) had an ED visit within 90 days before the index pregnancy. ED use in the first year of life was higher among infants whose mother had visited the ED before pregnancy (570 per 1000) vs those whose mother had not (388 per 1000) (RR, 1.19 [95% CI, 1.18-1.20]; ARD, 91.1 per 1000 [95% CI, 88.6-93.6 per 1000]). Compared with mothers without a prepregnancy ED visit, the RR of infant ED use in the first year was 1.19 (95% CI, 1.18-1.20) if its mother had 1 prepregnancy ED visit, 1.18 (95% CI, 1.17-1.20) following 2 visits, and 1.22 (95% CI, 1.20-1.23) after at least 3 maternal visits. A low-acuity maternal prepregnancy ED visit was associated with an adjusted odds ratio (aOR) of 5.52 (95% CI, 5.16-5.90) for a low-acuity infant ED visit, which was numerically higher than the pairing of a high-acuity ED use between mother and infant (aOR, 1.43, 95% CI, 1.38-1.49). Conclusions and Relevance: In this cohort study of singleton livebirths, prepregnancy maternal ED use was associated with a higher rate of ED use by the infant in the first year of life, especially for low-acuity ED use. This study's results may suggest a useful trigger for health system interventions aimed at reducing some ED use in infancy.