Systematic review shows pre-pregnancy weight loss interventions do not significantly reduce gestational diabetes mellitus risk in women with overweight or obesity

OBJECTIVE: To synthesize randomized controlled trials (RCTs) regarding the effectiveness of pre-pregnancy weight loss interventions on the risk of gestational diabetes mellitus (GDM) in women with overweight or obesity. METHODS: Comprehensive literature searches were conducted across nine databases from inception to May 2024. RCTs comparing pre-pregnancy weight loss interventions with blank control or active control among adult women with overweight or obesity were included. Meta-analyses, using a random-effects model, were performed to pool results of RCTs. RESULTS: Six studies, including 1632 participants, were included. The effectiveness of pre-pregnancy weight loss interventions on changes in weight and body mass index (BMI) was statistically significant (mean difference [MD] = -6.02, 95% confidence interval [CI] [-8.94, -3.10], I = 98%; MD = -2.22, 95% CI [-3.44, -1.00], I = 98%). However, there was no statistically significant difference in the risk of GDM in women receiving pre-pregnancy weight loss interventions compared with controls (Odd Ratio [OR] = 0.70, 95% CI [0.48, 1.03], I = 2%). LINKING EVIDENCE TO ACTION: Pre-pregnancy weight loss interventions do not significantly impact the risk of GDM in women with overweight or obesity. Due to the small number of studies, small sample size, and large heterogeneity of pre-pregnancy weight loss interventions, further research is required. TRIAL REGISTRATION: ClinicalTrials.gov identifier: CRD42023482808.