Context: Lifestyle interventions are recommended for women with obesity and infertility, but trial evidence is scarce, and none investigated interventions that continues during fertility treatment.
Objective: Evaluate the effectiveness of a lifestyle intervention compared with usual care on fertility outcomes in women with obesity and infertility.
Design: The Obesity-Fertility Randomized controlled trial, stratified for PCOS status.
Setting: Academic fertility clinic.
Participants: 127 women aged 18-40 years with infertility and obesity (body mass index ≥30 kg/m2, or ≥27 kg/m2 with polycystic ovary syndrome (PCOS)), excluding those unlikely to conceive naturally.
Intervention: The intervention group (IG) received a 6-month lifestyle intervention alone (individual follow-up with a dietician and kinesiologist, and group sessions) before adding fertility treatments. The control group (CG) received usual fertility care directly.
Main outcome measure: Live birth conceived within 18 months of randomization.
Results: Compared to CG, the IG lost more weight (-3.21±4.73% vs. -0.40±3.66%, p=0.003) and waist circumference (-2.62±4.46cm vs. -0.23±3.81cm, p=0.01) at 6 months. The live-birth rate was 44.4% in the IG (n=63) vs. 35.9% in the CG (n=64) (risk ratio (RR) (95%CI)=1.24 (0.81-1.90)). In the IG vs. CG, clinical pregnancy rates were 52.4% vs. 37.5% (RR=1.40 (0.94-2.07)) and natural pregnancy rates were 27.0% vs. 12.5% (RR=2.16 (1.01-4.64)).
Conclusion: Compared with usual care, a lifestyle intervention alone for 6 months and then combined with fertility treatments did not increase the 18-month rate of pregnancies leading to a live birth, but significantly increased natural pregnancy rates, potentially reducing the need for costly assisted reproduction in this population.
Keywords: Fertility; Lifestyle intervention; Live-birth; Obesity; Randomized Controlled Trial; Women.
© The Author(s) 2025. Published by Oxford University Press on behalf of the Endocrine Society.