Large-Scale Data Harmonization Across Prospective Studies

Abstract

The Preconception Period Analysis of Risks and Exposures Influencing Health and Development (PrePARED) Consortium creates a novel resource for addressing preconception health by merging data from numerous cohort studies. In this paper, we describe our data harmonization methods and results. Individual-level data from 12 prospective studies were pooled. The crosswalk-cataloging-harmonization procedure was used. The index pregnancy was defined as the first postbaseline pregnancy lasting more than 20 weeks. We assessed heterogeneity across studies by comparing preconception characteristics in different types of studies. The pooled data set included 114,762 women, and 25,531 (22%) reported at least 1 pregnancy of more than 20 weeks' gestation during the study period. Babies from the index pregnancies were delivered between 1976 and 2021 (median, 2008), at a mean maternal age of 29.7 (standard deviation, 4.6) years. Before the index pregnancy, 60% of women were nulligravid, 58% had a college degree or more, and 37% were overweight or obese. Other harmonized variables included race/ethnicity, household income, substance use, chronic conditions, and perinatal outcomes. Participants from pregnancy-planning studies had more education and were healthier. The prevalence of preexisting medical conditions did not vary substantially based on whether studies relied on self-reported data. Use of harmonized data presents opportunities to study uncommon preconception risk factors and pregnancy-related events. This harmonization effort laid the groundwork for future analyses and additional data harmonization.

Keywords: consortia; data harmonization; preconception period; pregnancy; pregnancy complications.

Figure 1

Compilation of the overall sample and the birth group in the Preconception Period Analysis of Risks and Exposures Influencing Health and Development (PrePARED) Consortium, 1973–present. ALSWH, Australian Longitudinal Study on Women’s Health; BHS, Bogalusa Heart Study; CARDIA, Coronary Artery Risk Development in Young Adults; EAGeR, Effects of Aspirin in Gestation and Reproduction; EPS, Early Pregnancy Study; GUTS, Growing Up Today Study; HCHS/SOL, Hispanic Community Health Study/Study of Latinos; HOPE, Home Observation of Periconceptional Exposures; LIFE India, Longitudinal Indian Family Health Pilot Study; NHS3, Nurses’ Health Study 3; PRESTO, Pregnancy Study Online; TTP, Time to Pregnancy in Couples of Proven Fecundity.

Figure 2

The crosswalk-cataloging-harmonization process used in the Preconception Period Analysis of Risks and Exposures Influencing Health and Development (PrePARED) Consortium, 1973–present. The example depicted pertains to the variable on cannabis use. CDE, common data element; NIH, National Institutes of Health.