Multiple Chronic Conditions Before Pregnancy and Risk of Adverse Maternal Health Outcomes: Population-Based Cohort Study.

Objective: To assess the risks of perinatal emergency department (ED) use, hospitalisation and severe maternal morbidity or mortality (SMM-M) associated with preconception MCC, according to the number of chronic conditions, complex MCC and co-occurring cardiometabolic conditions.

Design: Population-based cohort study.

Setting: Ontario, Canada.

Population: Females aged 13-54 years, with a recognised pregnancy, 2012-2021.

Methods: Modified Poisson regression was used to generate adjusted relative risks (aRRs) according to the number of chronic conditions, complex MCC (≥ 3 chronic conditions affecting ≥ 3 body systems) and co-occurring cardiometabolic conditions. aRRs were adjusted for age, parity, income quintile, rurality and immigrant/refugee status.

Main Outcome Measures: ED use, hospitalisation and SMM-M from the estimated date of conception to 42 days postpartum.

Results: In total, 894 042 individuals had no pre-pregnancy chronic condition; 357 398 had 1; 94 427 had 2; and 27 326 had ≥ 3 chronic conditions. Relative to those without a chronic condition, the aRR for ED use increased with 1 (1.26, 95% CI 1.25-1.27), 2 (1.55, 1.54-1.56) and ≥ 3 (1.86, 1.85-1.88) conditions. For hospitalisations, the corresponding aRRs were 1.45 (1.43-1.47), 2.06 (2.02-2.10) and 3.18 (3.09-3.27). For SMM-M, the corresponding aRRs were 1.38 (1.35-1.42), 1.82 (1.75-1.90) and 2.75 (2.59-2.92). SMM-M risk was even more pronounced with complex MCC (aRR 2.92, 95% CI 2.72-3.14), and ≥ 3 cardiometabolic conditions (aRR 5.45, 95% CI 4.29-6.91).

Conclusions: MCC, especially complex or cardiometabolic MCC, is associated with elevated risk of maternal morbidity. Multidisciplinary patient-centred care may mitigate these risks.