Prepregnancy Cardiovascular Health, Gestational Diabetes, and Coronary Artery Calcium

Importance: Poor cardiovascular health (CVH) and gestational diabetes (GD) are each associated with higher risk for cardiovascular disease (CVD). Individuals with poor CVH also have a higher risk of GD, but it remains unclear if GD mediates the association between prepregnancy CVH and CVD. Objective: To examine whether GD is a mediator or marker of the association between prepregnancy CVH and midlife subclinical CVD. Design, Setting, and Participants: This prospective, population-based cohort study was nested within the CARDIA (Coronary Artery Risk Development in Young Adults) study, which included self-identified Black and White women with up to 35 years of follow-up. This study was conducted at 4 US centers among women with at least 1 singleton birth from baseline through 15-year follow-up, available prepregnancy CVH data, available CAC data from 15- to 25-year follow-up, and no prepregnancy diabetes. Data for this study were collected from 1985 to 2010 and analyzed from 2021 to 2024. Exposure: Prepregnancy CVH, quantified using the American Heart Association's Life's Simple 7 (score 0-14) and stratified as low or moderate (0-10) and high (11-14) based on a median split. Main Outcomes and Measures: The primary outcome was CAC, quantified via computed tomography scans. Odds ratios (ORs) were calculated for GD and incident CAC greater than 0 among people with low or moderate CVH compared with high prepregnancy CVH adjusted for age, race, education, and parity. Causal mediation analyses estimated the proportion of the association between prepregnancy CVH and incident CAC mediated through GD. Results: Of 1052 included women, mean (SD) age was 28.6 (4.5) years; 501 individuals (47.6%) self-identified as Black, and 551 individuals (52.4%) self-identified as White. Women with lower (worse) compared with high (better) prepregnancy CVH were more likely to have a pregnancy complicated by GD (8.8% vs 6.3%; adjusted OR, 1.8; 95% CI, 1.1-3.0) and were more likely to develop CAC (28.2% vs 19.2%; adjusted OR, 1.7; 95% CI, 1.2-2.5). GD mediated 6% (95% CI, 0%-22%) of the association between prepregnancy CVH and incident CAC. Conclusions and Relevance: In this cohort study, less favorable prepregnancy CVH was associated with subclinical CVD in midlife, but only a small proportion of this association was mediated through GD. This suggests that GD predominantly represents a marker of prepregnancy CVH and emphasizes the importance of improving CVH early in the life course prior to pregnancy.