Prepregnancy adherence to dietary patterns and lower risk of gestational diabetes mellitus.

BACKGROUND Previous studies observed inverse associations of adherence to the alternate Mediterranean (aMED), Dietary Approaches to Stop Hypertension (DASH), and alternate Healthy Eating Index (aHEI) dietary patterns with risk of type 2 diabetes; however, their associations with gestational diabetes mellitus (GDM) risk are unknown. OBJECTIVE This study aimed to assess usual prepregnancy adherence to well-known dietary patterns and GDM risk. DESIGN Our study included 21,376 singleton live births reported from 15,254 participants of the Nurses' Health Study II cohort between 1991 and 2001. Pregnancies were free of prepregnancy chronic disease or previous GDM. Prepregnancy dietary pattern adherence scores were computed based on participants' usual intake of the patterns' components, assessed with a validated food-frequency questionnaire. Multivariable logistic regressions with generalized estimating equations were used to estimate the RRs and 95% CIs. RESULTS Incident first-time GDM was reported in 872 pregnancies. All 3 scores were inversely associated with GDM risk after adjustment for several covariables. In a comparison of the multivariable risk of GDM in participants in the fourth and first quartiles of dietary pattern adherence scores, aMED was associated with a 24% lower risk (RR: 0.76; 95% CI: 0.60, 0.95; P-trend = 0.004), DASH with a 34% lower risk (RR: 0.66; 95% CI: 0.53, 0.82; P-trend = 0.0005), and aHEI with a 46% lower risk (RR: 0.54; 95% CI: 0.43, 0.68; P-trend < 0.0001). CONCLUSION Prepregnancy adherence to healthful dietary patterns is significantly associated with a lower risk of GDM.