Objective: To compare reporting of severe maternal morbidity (SMM) in birth certificate versus hospital claims data and evaluate differences by patient race/ethnicity. Methods: We compared incidence rates of blood transfusion, hysterectomy, intensive care unit admission, uterine rupture, and 3 rd /4 th degree perineal laceration between 2019 deliveries in the US birth certificate and the Premier Healthcare Database, overall and stratifying by maternal race/ethnicity. We then computed incidence rate ratios (IRRs) computed between datasets, and fit logistic regression models of race/ethnicity on SMM. Results: Comparing 3,467,934 birth certificate deliveries with 3,450,569 Premier deliveries (n=905,766 pre-weighting for national representativeness), incidence rates of SMMs were lower in birth certificate compared with Premier data, and these rate differentials varied by maternal race/ethnicity. For example, among non-Hispanic white patients, the incidence rate of blood transfusions in birth certificate data was 50% that of the incidence rate in the Premier claims dataset (IRR: 0.50, 95% CI: 0.47, 0.52). Among all other races/ethnicities, the incidence rate of blood transfusions was even lower relative to the claims data (IRR range: 0.29-0.39). Adjusted odds ratios (aOR) for SMM in non-Hispanic Black and Hispanic patients versus non-Hispanic white patients were closer to the null in birth certificate than Premier data (e.g., compared with non-Hispanic white patients, non-Hispanic Black patients had a 16% higher adjusted odds in the birth certificate (95% CI: 1.10, 1.21) data versus an 84% higher adjusted odds of blood transfusion in Premier data (95% CI: 1.79, 1.89)). Conclusions: Birth certificates report substantially less SMM than claims data, with greater differential in reporting for non-Hispanic Black and Hispanic patients that may bias birth certificate-based research findings.
Pineles et al. (Mon,) studied this question.