NSAID Exposure During Pregnancy

We considered pregnant women prescribed ≥2 NSAIDs during the etiologically relevant window to be defined as those exposed to NSAIDs; if a woman refilled her prescription for NSAIDs, we assumed that she probably took them. The etiologically relevant window for major congenital malformations (cohort 1) was defined as the first trimester and for low birth weight, antepartum hemorrhage, and oligohydramnios (cohort 2) as early pregnancy. Pregnancies were considered unexposed if not prescribed any NSAIDs from 90 days before the LMP throughout the end of the first trimester or end of early pregnancy for cohorts 1 and 2, respectively. The LMP date was estimated by using a previously validated algorithm to estimate gestational age in administrative healthcare databases [25 (link)].