Neonatal and maternal adverse outcomes and exposure to nonsteroidal antiinflammatory drugs during early pregnancy in South Korea: A nationwide cohort study

BACKGROUND: Existing data on the use of nonsteroidal anti-inflammatory drugs (NSAIDs) during late pregnancy is well established, providing assurance. However, the use of NSAIDs during early pregnancy remains inconclusive owing to conflicting findings on adverse neonatal outcomes as well as the limited data on adverse maternal outcomes. Therefore, we sought to investigate whether early prenatal exposure to NSAIDs was associated with neonatal and maternal adverse outcomes. METHODS AND FINDINGS: We conducted a nationwide, population-based cohort study using Korea’s National Health Insurance Service (NHIS) database with a mother–offspring cohort constructed and validated by the NHIS to include all live births in women aged 18 to 44 years between 2010 and 2018. We defined exposure to NSAIDs as at least two records of NSAID prescriptions during early pregnancy (first 90 days of pregnancy for congenital malformations and first 19 weeks for nonmalformation outcomes) and compared against three distinct referent groups of (1) unexposed, no NSAID prescription during the 3 months before pregnancy start to end of early pregnancy; (2) acetaminophen-exposed, at least two acetaminophen prescriptions during early pregnancy (i.e., active comparator); and (3) past users, at least two NSAID prescriptions before the start of pregnancy but no relevant prescriptions during pregnancy. Outcomes of interest were adverse birth outcomes of major congenital malformations and low birth weight and adverse maternal outcomes of antepartum hemorrhage and oligohydramnios. We estimated relative risks (RRs) with 95% CIs using generalized linear models within a propensity score (PS) fine stratification weighted cohort that accounted for various potential confounders of maternal sociodemographic characteristics, comorbidities, co-medication use, and general markers of burden of illness. Of 1.8 million pregnancies in the PS weighted analyses, exposure to NSAIDs during early pregnancy was associated with slightly increased risks for neonatal outcomes ...