O-286 Weight loss interventions prior to infertility treatment does it make sense?
Authors: Hoek A , Wang Z , Cantineau A , Groen H , Wang R , Mol B 
Published: July 2024

Abstract
Obesity in women is negatively associated with reproductive outcomes such as decreased natural conception and pregnancy rate in assisted reproductive technique (ART), as well as increased risks of miscarriage and maternal and foetal complications, including risks of perinatal and neonatal death. The reproductive consequences of obesity stem from a combination of ovarian, uterine and systemic pathophysiological changes, although not all fully elucidated. These alterations contribute to reduced oocyte and embryo quality, reduced uterine receptivity and systemic inflammatory responses.
Various guidelines recommend lifestyle interventions based on dietary and/or physical activity targeting at a 5 to 10% reduction in body weight as an initial step prior to fertility treatment for women with infertility and overweight or obesity. However, evidence from well powered randomised controlled trials (RCTs) assessing the effectiveness of lifestyle interventions aiming at weight loss prior to fertility treatments is scarce and not unequivocally positive with respect to reproductive outcomes.
First, this presentation will focus on the effectiveness of pre-conception lifestyle intervention targeting weight loss, on reproductive outcomes documented in the latest systematic review (SR) and meta-analysis and preliminary results of an individual participant data meta-analysis (IPDMA).
The latest SR in 2021 (Obesity reviews DOI: 10.1111/obr.13325) including 15 RCTs until March 2020 (N = 1852 women) suggests more weight loss in the intervention group. An increase in live birth rates (LBR) in nine RCTs (N = 1203 women) and a higher natural conception rate following lifestyle intervention compared to no intervention were reported. However, no effect of lifestyle intervention preceding ART in six RCTs (N = 1040 women). With respect to potential harm of lifestyle intervention there is no significant increased risk of early pregnancy loss. Complications during pregnancy, such as early pregnancy loss and maternal, fetal and neonatal outcomes are underreported in most included studies.
The VENUS IPDMA (BMJ Open 2022;12:e065206) analyzed individual patient data of 11 RCTs of 14 eligible RCTs (N = 1903 participants; 1010 in the intervention group and 893 in the control group). Preliminary data (abstract ESHRE 2023) showed that physical activity and/or dietary interventions prior to fertility treatment resulted in more weight reduction compared to those in the control group in 11 RCTs. The intervention group, however, did not have a significantly higher rate of LBR in nine RCTs (N = 1702 participants). Compared to the control group, the intervention group had smaller waist and hip circumference, lower systolic and diastolic blood pressure, and lower triglycerides, total cholesterol, glucose, and insulin levels at the time of study follow up.
Do we have a definitive answer to the question: “weight loss interventions prior to fertility treatment; does it make sense” using data of IPDMA? Shortcomings of the available evidence regarding the effectiveness and safety of dietary and/or physical activity interventions in women with overweight or obesity prior to fertility treatments will be presented. Limitations of the studies and future perspectives and challenges in this field of research will be highlighted. Finally, the question “does it make sense” is broader than the effectivity of the intervention. Do we as clinicians adopt our role as health advocates to advice and guide future parents to adopt a healthy lifestyle, with weight reduction as a result? Could this lead to a healthier lifestyle for the future of parents and children? To conclude: “does it make sense” is not an easy question to answer.