Prepregnancy Diet Quality Linked to Lower Pregnancy Risks

A healthier prepregnancy diet was associated with lower risks of adverse pregnancy outcomes, particularly preterm birth and hypertensive disorders of pregnancy, in a cohort study published in JAMA Network Open.

The analysis used data from the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-Be and its Heart Health Study and included 7551 nulliparous participants who met eligibility criteria; their mean age was 27.3 years. Participants completed the Block/Bodnar 2010 food frequency questionnaire at 6 to 13 weeks’ gestation. Investigators developed the Prepregnancy Dietary Quality Index from 23 adequacy and 4 moderation components, with scores ranging from 0 to 100 and higher scores indicating healthier diets.

The primary outcome was a composite of 1 or more adverse pregnancy outcomes: hypertensive disorders of pregnancy, preterm birth, small for gestational age, stillbirth, or gestational diabetes. Participants were divided into quartiles from Q1, representing the least healthy diets, to Q4, representing the healthiest. Adjusted relative risks were estimated with modified Poisson regression.

Compared with Q1, Q4 was associated with lower risks of the composite outcome (adjusted relative risk [aRR], 0.77; 95% CI, 0.66-0.89), preterm birth (aRR, 0.73; 95% CI, 0.55-0.97), and hypertensive disorders of pregnancy (aRR, 0.77; 95% CI, 0.62-0.95). Q3 was also associated with a lower risk of preterm birth (aRR, 0.76; 95% CI, 0.59-0.98).

Across increasing diet-quality quartiles in the 3520-participant Heart Health Study cohort, median insulin, triglyceride, and hs-CRP levels decreased, while median HDL-C increased. The authors noted that dietary intake was self-reported and could be affected by recall and reporting bias. They also identified possible selection bias from excluding participants with missing dietary or biomarker data and called for validation of the index in more diverse populations.

Source: Bharmal U, Saade G, Greenland P, et al. Prepregnancy diet quality index and adverse pregnancy outcomes. JAMA Netw Open. 2026;9(9):e2633245. doi:10.1001/jamanetworkopen.2026.33245