Impact of Mediterranean Diet Adherence During Pregnancy on Preeclampsia, Gestational Diabetes Mellitus, and Excessive Gestational Weight Gain: A Systematic Review of Observational Studies and Randomized Controlled Trials

Abstract

Background/Objectives: There is limited evidence on the association between maternal Mediterranean diet (MD) adherence and risks of preeclampsia, gestational diabetes mellitus (GDM), and excessive gestational weight gain (eGWG), and hence a systematic review of observational studies and randomized controlled trials was conducted. Methods: A total of 30,930 articles from the Scopus, EMBASE, PubMed, MEDLINE, and Google Scholar databases were identified, published between January 2000 and April 2025. The National Institutes of Health Quality Assessment Tool and the Cochrane Risk of Bias Tool 2.0 were used to assess the quality of seven studies (one each were case-control and cross-sectional, three were RCTs, and two were prospective cohort studies). Results: Overall, the studies examined the risks of preeclampsia (four studies), GDM (five studies), and eGWG (three studies). Only one prospective cohort study out of four reported that MD adherence was associated with lower risk of preeclampsia (OR 0.78; 95% CI: 0.64 to 0.96 for highest vs. lowest tertile). MD adherence was associated with decreased risk of GDM in the intervention groups in four studies (two RCTs (OR: 0.75, 95% CI 0.57 to 0.98 and OR: 0.72, 95% CI 0.50 to 0.97) and one each of cross-sectional (OR: 2.32; 95% CI 2.13 to 2.57 for a 1-point decrease in the dietary score) and case-control studies (high Vs. low MD adherence: OR: 0.20, 95% CI 0.50 to 0.70)). MD adherence was associated with decreased risk of eGWG in two studies: one RCT (RR: 0.91, 95% CI 0.86 to 0.96 for a 1-point increment in the MD score) and one cross-sectional study (OR: 1.78; 95% CI 1.51 to 2.02 for a 1-point decrease in the MD score). Conclusions: Findings indicated the protective associations between MD adherence and GDM and eGWG risks but not for preeclampsia.