Brain Natriuretic Peptide Screening in Pregnancy and Association with Severe Maternal Morbidity during Delivery Hospitalization

This study aimed to describe patterns of outpatient natriuretic peptide (NP) testing and levels, including brain NP (BNP) and N-terminal pro-BNP (NT-proBNP), among pregnant patients with and without heart disease (HD) and the association between NP and severe maternal morbidity (SMM).A nationwide sample of pregnant patients delivering at ≥20 weeks in the Epic Cosmos dataset from 2017 to 2023 was extracted. Outpatient NP levels drawn between 24 and 34 weeks' gestation were identified, categorized as normal or elevated (BNP ≥ 100 or NT-proBNP ≥ 300 pg/mL), and described according to the presence or absence of congenital or acquired HD based on ICD-10 codes. The primary outcomes were CDC-defined SMM and nontransfusion SMM. Among those with NP testing, the association between elevated levels and SMM was assessed using logistic regression after applying stabilized inverse probability treatment weights (SIPTW) that included demographic characteristics, HD, obesity, and other medical comorbidities.Of 3,935,745 unique pregnancies, 3,920,088 (99.6%) had no NP testing, 14,180 (0.4%) had normal NP, and 1,477 (0.04%) had elevated NP. Of those with any HD, 1.6% underwent NP testing. A greater proportion of those with normal NP (<i>N</i> = 1,287 [9.1%]) and elevated NP (<i>N</i> = 406 [27.5%]) experienced SMM compared with those without NP testing (<i>N</i> = 99,176 [2.5%]; <i>p</i> < 0.001), with similar results for nontransfusion SMM. The odds of SMM and nontransfusion SMM were higher in patients with elevated NP levels; this association persisted, but was attenuated, in SIPTW-adjusted models (SMM crude odds ratio [OR]: 14.6, 95% confidence interval [CI]: 13.0, 16.4, and adjusted odds ratio [aOR]: 1.2, 95% CI: 1.1, 1.2; nontransfusion SMM crude OR: 25.4, 95% CI: 22.6, 28.6 and aOR: 1.2, 95% CI: 1.2, 1.2).NP testing remains underutilized during pregnancy, even among patients with heart disease. Elevated levels are associated with higher SMM risk, although the attenuation in association after covariate adjustment suggests its additive value in predicting SMM may be limited. · BNP testing remains underutilized in pregnancy.. · BNP testing ranged from only 1 to 6% of individuals with heart disease in pregnancy.. · Elevated BNP levels obtained prior to delivery are associated with SMM, although this association is attenuated after adjustment for other clinical risk factors..