Background: To estimate associations between facets of the maternal childhood family environment with gestational diabetes (GDM) and to test mediation by pre-pregnancy waist circumference.

Methods: We used data from CARDIA, a cohort of individuals aged 18-30 years at baseline (1985-86), followed over 30 years (2016). We included participants with one or more pregnancies ≥ 20 weeks after baseline, without pre-pregnancy diabetes. The primary exposure was the Childhood Family Environment Scale (assessed year 15), including the total score and abuse, nurture, and stability subscales as continuous, separate exposures. The outcome was GDM (self-reported at each visit for each pregnancy). We fit log binomial models with generalized estimating equations to calculate risk ratios (RR) and 95% confidence intervals (CI), adjusting for age at delivery, parity, race (Black or White), and parental education. We used regression models with bootstrapped CIs to test mediation and effect modification by excess abdominal adiposity at the last preconception CARDIA visit (waist circumference ≥ 88 cm).

Results: We included 1033 individuals (46% Black) with 1836 pregnancies. 130 pregnancies (7.1%) were complicated by GDM. For each 1 point increase on the abuse subscale (e.g., from "rarely or never" to "some or little of the time") there was a 30% increased risk of GDM (RR: 1.3, 95% CI: 1.0, 1.7). There was evidence of effect modification but not mediation by preconception abdominal adiposity.

Conclusions: A more adverse childhood family environment was associated with increased risk of GDM, with a stronger association among individuals with preconception waist circumference ≥ 88 cm.