Effect of lifestyle or metformin interventions before IVF/ICSI treatment on infertile women with overweight/obese and insulin resistance: a factorial design randomised controlled pilot trial

BACKGROUND: For infertile women with overweight/obesity and insulin resistance (IR), it is uncertain whether intervention before infertility treatment can improve live birth rate (LBR). We implemented a factorial-design study to explore the effectiveness of lifestyle and metformin interventions. This pilot study aimed to evaluate the feasibility of a definitive study. METHODS: We randomised 80 women without polycystic ovarian syndrome (PCOS) who planned to start their first or second IVF/ICSI treatment with a body mass index ≥ 25 kg/m(2) and IR. Participants were randomised (1:1:1:1) into four groups: (A) lifestyle intervention, (B) metformin intervention, (C) lifestyle + metformin intervention, or (D) no intervention. All interventions were performed before IVF/ICSI treatment. RESULTS: During 10 months, 114 women were screened and eligible; 80 were randomised, and 72 received the assigned treatment. The recruitment rate was 70.18% (80/114, 95% CI 61.65%–78.70%). An average of 10 participants were randomised each month. None of the participants crossed over from one group to another. Approximately 93.15% (68/73) of the participants achieved good intervention compliance. Only 77.78% (56/72) of the recruited participants started infertility treatment after achieving the goal of the intervention. All randomised participants completed the follow-up. Mild adverse events after metformin administration were reported in 43.24% (16/37) of the cases, although no serious adverse events related to the interventions occurred. The LBR for groups A + C and B + D were 33.33% (12/36) and 33.33% (12/36) (RR = 1.00, 95%CI:0.52–1.92) (lifestyle intervention effect). The LBR for groups B + C and A + D were 43.24% (16/37) and 22.86% (8/35) (RR = 1.89, 95% CI:0.93–3.86) (metformin intervention effect). There was no evidence for an intervention interaction between lifestyle and metformin. We cannot yet confirm the effects of lifestyle, metformin, or their interaction owing to the insufficient sample size in this pilot study. CONCLUSIONS: Instituting a 2 × 2 factorial design randomized controlled trial (RCT) is feasible, as the pilot study showed a high recruitment rate and compliance. There is no evidence that lifestyle or metformin improves live birth, and adequately powered clinical trials are required. TRIAL REGISTRATION: clinicaltrials.gov NCT03898037. Registered: April 1, 2019. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40814-023-01388-x.