Association between the dietary obesity-prevention score and risk of gestational diabetes mellitus: an exploratory subgroup analysis.

BACKGROUND: Gestational diabetes mellitus (GDM) presents significant risks to maternal and offspring health. Modifiable factors like dietary quality are important for prevention. The Dietary Obesity-Prevention Score (DOS) is a validated tool for assessing obesity-related dietary quality. Nevertheless, its association with GDM remain unclear. This study aimed to examine the relationship between DOS and GDM risk. METHOD: This prospective cohort included 1,894 pregnant women across nine medical centers in China. Dietary intake was assessed by 3-day 24-h recalls. The DOS was derived from 6 food groups. Multivariable binary logistic regression, component analysis, subgroup analysis, and restricted cubic splines (RCS) were used to evaluate associations. RESULTS: In the overall population, DOS showed no significant association with GDM (OR = 0.944, 95% CI: 0.879-1.015). The interaction between DOS and energy intake status was not significant (p for interaction = 0.193). Exploratory subgroup analyses showed that among women with inadequate energy intake, higher DOS was associated with reduced GDM risk (OR = 0.867, 95% CI: 0.773-0.973). Likelihood ratio tests showed that excluding fruit from the full model worsened the model fit (Δ-2LL = 16.091, df = 1, p < 0.001). Component analysis suggested a possible inverse association between fruit intake and GDM risk (OR per 50 g/1,000 kcal = 0.905, 95% CI: 0.817-1.001, p = 0.053). Fruit intake was associated with lower GDM risk in the middle DOS tertile (OR = 0.783, 95% CI: 0.620-0.990, p = 0.041) and showed a borderline significant association in the high DOS tertile (OR = 0.828, 95% CI: 0.686-1.000, p = 0.049). In the inadequate energy intake subgroup, RCS analysis revealed a non-linear association between fruit intake and GDM risk (p for non-linearity = 0.048), with risk decreasing to a nadir at approximately 400 g/day, after which it stabilized. The 95% CI widened beyond 600 g/day due to sparse data, and these inflection points should be interpreted as exploratory descriptive features rather than precise thresholds. CONCLUSION: In pregnant women with inadequate energy intake, higher dietary quality was associated with reduced GDM risk. Fruits may play a role, although these findings are exploratory and require confirmation in independent cohorts.