Examining the Prevalence Rates of Preexisting Maternal Medical Conditions and Pregnancy Complications by Source: Evidence to Inform Maternal and Child Research.

Objectives We sought to examine whether there are systematic differences in ascertainment of preexisting maternal medical conditions and pregnancy complications from three common data sources used in epidemiologic research. Methods Diabetes mellitus, chronic hypertension, gestational diabetes mellitus (GDM), gestational hypertensive disorders (GHD), placental abruption and premature rupture of membranes (PROM) among 4821 pregnancies were identified via birth certificates, maternal self-report at approximately 4 months postpartum and by discharge codes from the Statewide Planning and Research Cooperative System (SPARCS), a mandatory New York State hospital reporting system. The kappa statistic (k) was estimated to ascertain beyond chance agreement of outcomes between birth certificates with either maternal self-report or SPARCS. Results GHD was under-ascertained on birth certificates (5.7 %) and more frequently indicated by maternal report (11 %) and discharge data (8.2 %). PROM was indicated more on birth certificates (7.4 %) than maternal report (4.5 %) or discharge data (5.7 %). Confirmation across data sources for some outcomes varied by maternal age, race/ethnicity, prenatal care utilization, preterm delivery, parity, mode of delivery, infant sex, use of infertility treatment and for multiple births. Agreement between maternal report and discharge data with birth certificates was generally poor (kappa < 0.4) to moderate (0.4 ≤ kappa < 0.75) but was excellent between discharge data and birth certificates for GDM among women who underwent infertility treatment (kappa = 0.79, 95 % CI 0.74, 0.85). Conclusions for Practice Prevalence and agreement of conditions varied across sources. Condition-specific variations in reporting should be considered when designing studies that investigate associations between preexisting maternal medical and pregnancy-related conditions with health outcomes over the life-course.