Dose-response association between dietary patterns and gestational diabetes mellitus risk: A systematic review and meta-analysis of observational studies.

Although dietary factors are relevant modifiable risk factors for gestational diabetes mellitus (GDM), the exact association between dietary patterns and GDM remains controversial. Therefore, a systematic review and dose-response meta-analysis of observational studies were conducted to summarize the association between dietary patterns and risk of GDM. PubMed, Scopus, Web of Science, Cochrane Library, and EMbase databases were systematically searched for publications up to March 10, 2020. All observational studies which assessed the risk of GDM according to the categories of healthy or unhealthy dietary patterns derived by either a priori or a posteriori methods were eligible to be included. Pooled effect sizes for the highest vs. lowest categories of healthy/unhealthy dietary patterns were calculated using the random-effects model. Linear and nonlinear dose-response analyses were performed to determine dose-response associations. Thirty-one studies were included, of which 26 studies (80,849 participants) assessed healthy dietary pattern and 15 studies (32,965 participants) assessed the unhealthy dietary pattern. Individuals with a higher adherence to the healthy dietary pattern were less likely to be affected by GDM (RR = 0.86; 95% CI: 0.76-0.96; I 2  = 56.2%). There was a marginally significant association between unhealthy dietary patterns and GDM risk (RR = 1.28; 95% CI: 0.99-1.67; I 2  = 74.7). Significant linear associations were observed between healthy ( p  = .011) and unhealthy ( p  = .009) dietary patterns and GDM risk. Pregnant women with a healthier dietary pattern (a diet rich in fruits, vegetables, and whole grains) had lower risk for GDM. In contrast, higher adherence to an unhealthy dietary pattern was associated with increased risk of GDM. Further longitudinal studies are needed to confirm the results.