Pre-IVF lifestyle intervention and reproductive outcomes in women with overweight or obesity undergoing IVF: a randomized clinical trial

Obesity is associated with reduced female fertility and poorer in vitro fertilization (IVF) outcomes. Although pre-IVF lifestyle-based weight loss is commonly recommended for women with overweight or obesity, whether specific strategies improve reproductive outcomes remains uncertain. We compared two pre-IVF lifestyle interventions with usual care in women undergoing IVF. In this single-center, parallel-group randomized clinical trial conducted at Shengjing Hospital of China Medical University, Shenyang, China, women aged 20–38 years with a body mass index (BMI) of 24–40 kg/m² planning IVF were randomly assigned in a 1:1:1 ratio to 12-hour time-restricted feeding plus moderate physical activity (TRF + PA), a calorie-restricted diet (CRD), or usual care. Recruitment took place from March 14, 2023, to August 20, 2024, and follow-up was completed on February 20, 2026. The primary outcome was cumulative live birth. Secondary outcomes included cumulative clinical pregnancy, miscarriage, obstetric complications, embryological outcomes, anthropometric changes, and metabolic measures. A total of 273 women underwent randomization. Cumulative live birth did not differ between groups, occurring in 46.6% of women in the TRF + PA group, 43.8% in the CRD group, and 44.0% in the control group (P = 0.916). After adjustment for baseline waist circumference, neither intervention was associated with cumulative live birth compared with usual care (TRF + PA vs. control: adjusted risk ratio [aRR] 1.034; 95% CI, 0.746–1.434; P = 0.839; CRD vs. control: aRR 0.936; 95% CI, 0.676–1.295; P = 0.689). TRF + PA was associated with a greater reduction in homeostasis model assessment of insulin resistance (HOMA-IR) than usual care ( P = 0.005). In analyses treating anthropometric change as a continuous exposure, greater reduction in body fat percentage was independently associated with a higher probability of live birth (per 1-percentage-point reduction: aRR 1.065; 95% CI, 1.021–1.111; P = 0.003). Exploratory spline analyses suggested a threshold, with higher live birth probability observed above an absolute reduction of 5.16% points in body fat percentage. Among women with overweight or obesity undergoing IVF, pre-IVF lifestyle intervention did not improve cumulative live birth compared with usual care. However, reduction in body fat percentage was independently associated with live birth, suggesting that change in adiposity may be more relevant to reproductive outcomes than weight loss alone. Chinese Clinical Trial Registry, ChiCTR2500112593. Registered on November 17, 2025; retrospectively registered.