The Effect of Lifestyle Intervention on Pregnancy and Birth Outcomes on Obese Infertile Women: A Systematic Review and Meta-Analysis

Background: Obesity has been associated to negative effects on natural fertility and a worse prognosis when assisted reproduction techniques are performed. Patients attending for fertility treatments are often advised to optimize their weights to improve outcomes. There are doubts about how effective are weight-loss interventions for improving fertility in women who are overweight or obese. Materials And Methods: We conducted a systematic review according to a registered protocol (PROSPERO registration number: CRD42017074964) to evaluate whether weight loss achieved by lifestyle program improves natural or assisted reproduction in obese infertile women. We searched CENTRAL, MEDLINE and EMBASE up to March 2018. Two reviewers selected randomised trials assessing a lifestyle intervention in women with obesity preceding a treatment for infertility and appraised their risk of bias. We extracted data on pregnancy, birth and miscarriage rates as primary outcomes and pooled effect estimates using a random effects model. The primary outcome was live birth rate. The summary measures were reported as relative risk (RR), 95% confidence interval (CI) and percentage of heterogeneity (I2). Results: We included eight randomised trials with 1175 women. Lifestyle programmes, improved pregnancy rates (RR 1.43, CI 95% 1.02 to 2.01; I2=60%; 8 RCTs; N=1098) but have no impact on live births (RR 1.39, CI 95% 0.90 to 2.14; I2=64%; 7RCTs; N=1034). Our findings suggest that women participating in lifestyle interventions had an increased risk of miscarriage (RR 1.50, CI 95% 1.04 to 2.16; I2=0; 6RCTs; N=543). We rated the quality of evidence for these outcomes as moderate to low. Conclusion: Lifestyle interventions slightly increase pregnancy rate and it is uncertain that it can improve live birth; furthermore they can increase miscarriage. More research is needed to further explore lifestyle interventions on reproductive outcomes in obese infertile women.