To assess health service use between days 43 and 365 postdelivery, comparing individuals with and without severe maternal morbidity (SMM).

Population-based cohort study.

Linked datasets from Population Data BC in British Columbia, Canada, April 2013–March 2021.

Postpartum individuals aged >18 years with a hospital or home delivery, with/without SMM occurring from 20 weeks’ gestation through 42 days post partum. Ectopic pregnancies, missing identifiers and maternal deaths at delivery or within 42 days post partum were excluded.

The primary outcome was high health service use, defined as being in the 95th percentile for use of one or more of the following non-obstetric visits: emergency department, hospitalisations and outpatient visits to a primary care physician or specialist—each occurring between 43 and 365 days after delivery hospitalisation discharge. Secondary outcomes included being in the 95th percentile for each visit type. Log binomial regression assessed the rate and risk of high health service use in SMM compared with non-SMM pregnancies, adjusting for confounders.

The cohort included 261 287 deliveries (5575 (2.1%) with SMM). Those with >15 visits within 43–365 days postdelivery were classified as having high health service use. SMM-affected individuals were twice as likely to have high health service use (9.2% vs 4.3%; adjusted relative risk (aRR)=1.96, 95% CI 1.78 to 2.17). Individuals with non-hypertensive cardiovascular SMM had markedly higher health service use (21.4% vs 4.3%; aRR=5.18, 95% CI 3.28 to 8.16). There was heterogeneity in the association between SMM and high health service use among those without versus with previous comorbidities, without versus with high service use in the 2 years prior to delivery, and without vs with preterm birth.

Our study revealed high health service use after SMM. These findings can help guide the development of standardised postpartum care pathways.