Effect of weight loss intervention on assisted reproductive outcomes in women with obesity and infertility: a retrospective cohort study

Objective: fertilization (IVF) without weight loss in women with obesity and infertility (body mass index [BMI] ≥30 kg/m²). Methods: A total of 308 women with obesity and infertility who underwent ART at Yancheng Maternal and Child Health Hospital between January 2022 and June 2024 were included. After excluding those with missing covariates and performing 1:1 propensity score matching (PSM), 58 patients were assigned to the Target-oriented Group (comprehensive weight loss intervention, including low-calorie diet, physical activity enhancement, and orlistat (120 mg three times daily) as a pharmacological adjunct to reduce fat absorption, aiming to achieve an 8% weight reduction) and 58 to the Standard Lifestyle Group (general lifestyle advice without specific weight loss targets). Because the weight-loss program inherently delayed ART initiation by approximately 16 weeks, a 16-week landmark analysis was performed to align the exposure assessment window between groups and minimize immortal time bias; only women who remained under active follow-up and were event-free at week 16 were included in the analysis. Results: = 0.004). In the 16-week landmark cohort, the Target-oriented Group demonstrated a higher likelihood of achieving clinical pregnancy than the Standard Lifestyle Group (adjusted hazard ratio [HR] 2.86, 95% confidence interval [CI]: 1.31-6.22). No significant between-group differences were observed in multiple pregnancy rate (3/23 [13.04%] vs. 1/9 [11.11%]), mean neonatal birth weight (3.33 ± 0.36 kg vs. 3.40 ± 0.60 kg), or neonatal complications (2/31 [6.45%] vs. 0/10 [0%]) (all P > 0.05). Conclusion: Although this retrospective study design limits causal inference, a 16-week intensive goal-directed weight loss intervention appeared to be associated with both significant weight reduction and higher live birth rates among women with obesity and infertility, in comparison with immediate IVF without prior weight management.