The AMerican PREGNANcy-Mother-Child CohorT (AM-PREGNANT): Description and prevalence of baseline outcomes and medication dispensing

Lisiane F Leal¹Odile Sheehy¹Jessica Gorgui¹Anick Bérard^1,2,3*

• ¹Centre de Recherche, Centre Hospitalier Universitaire Sainte-Justine, Montréal, Canada
• ²Montreal University, Montreal, Canada
• ³Université Claude Bernard Lyon 1, Lyon, Rhône-Alpes, France

We aim to present the AMerican PREGNANcy-Mother-Child CohorT (AM-PREGNANT) and its maternal and linked-children characteristics. Methods AM-PREGNANT was built using the Merative™ MarketScan® Commercial Database. We updated and implemented a hierarchical algorithm, using ICD-9-CM and ICD-10-CM codes to identify pregnancies in individuals aged 15 to 45 years (2003-2021). A unique family identifier linked mothers and their children. Enrollment required continuous coverage for 90 days before, during, and 42 days after pregnancy for mothers, and one year after birth for linked children. Pregnancy outcomes were categorized into deliveries, spontaneous abortions, and induced abortions. We characterized AM-PREGNANT (2004-2020) by sociodemographic factors, pregnancy history, comorbidities, and medication dispensing by pregnancy outcome. Medication dispensing, identified by filled prescriptions using drug claims, included 90 days before pregnancy until the last menstrual period, throughout pregnancy, and from delivery to postpartum period. Linked-children were assessed for low birth weight, preterm birth, congenital malformations, and other characteristics. Maternal and gestational age distributions were compared with U.S. national estimates.We identified 7,991,200 pregnancies from 6,079,647 persons (2003-2021). Continuous enrollment and a study period restricted to 2004-2020 resulted in 4,767,208 pregnancies. Of these, 76.9% resulted in deliveries, 17.3% were spontaneous abortions, and 5.9% were induced abortions. The linked mother-child cohort established comprises 2,578,990 pregnancies. Mean maternal age in the linked mother-child cohort was 30.4 years (SD 5.4). Mean gestational age at delivery was 38.6 weeks. Infections were the most prevalent maternal comorbidity (11.8%). Among deliveries, prevalence of medication dispensing in mothers before, during, and after pregnancy were 63.2%, 88.7%, and 82.9%, respectively. Among linked children, 52.1% were male, 12.0% were preterm, and 4.5% had low birth weight. The prevalence of major congenital malformations was 13.1%. Characteristics of children with continuous enrollment were similar to those without, except for medication dispensing during the first year of life (62.9% vs. 45.6%). Both maternal and gestational ages distributions of AM-PREGNANT were comparable to the US national estimates. Conclusions AM-PREGNANT is a valuable cohort for studying medication safety in mothers and children. Strict enrollment criteria ensure reliable data, minimizing the risk of misclassification. This cohort is a key resource for multi-country perinatal pharmacoepidemiology studies.