A University of Oxford-led review found that women with obesity who underwent structured weight loss before IVF were 47 % more likely to conceive naturally and 21 % more likely to become pregnant overall, suggesting weight management could reduce the need for treatment
Researchers led by the University of Oxford have found that structured weight loss before starting IVF treatment can significantly improve the chances of conceiving naturally. The findings highlight the potential for lifestyle changes to play a key role in reproductive health and reduce reliance on IVF.
The findings are detailed in the Annals of Internal Medicine.
Weight loss and IVF
In England, NHS commissioning bodies restrict access to NHS-funded IVF for women with a Body Mass Index (BMI) over 30.
The research team analysed 12 international trials, which included 1,921 women. It looked at synthesised evidence from a wide range of weight loss interventions, such as diet programmes, exercise, and weight loss medications such as orlistat and older GLP-1 agonists.
Dr Moscho Michalopoulou, lead author from Oxford’s Nuffield Department of Primary Care Health Sciences, said: “Currently, women with obesity can face a double challenge with higher rates of infertility and potential exclusion from NHS-funded IVF. Our findings offer hope. They suggest that offering structured weight loss support could improve the chance of conceiving naturally, which may avoid the need for IVF treatment. Programmes that help women achieve greater weight losses have the potential to help more women achieve a successful outcome, and should be tested in larger high-quality trials.”
47% more likely to conceive naturally after weight loss
The researchers found that women with obesity who participate in weight loss programmes before starting in vitro fertilisation (IVF) are 47% more likely to conceive naturally than those receiving minimal or no weight loss support, according to the most comprehensive systematic review of the evidence to date.
Beyond the increase in natural conception, the study found weight loss interventions increased the odds of any pregnancy (naturally or by IVF) by 21%.
The study suggests that providing structured weight loss support could help women become eligible for NHS IVF treatment and also increase their chances of conceiving without assistance.
Dr Moscho Michalopoulou, lead author from Oxford’s Nuffield Department of Primary Care Health Sciences, said: “Currently, women with obesity can face a double challenge with higher rates of infertility and potential exclusion from NHS-funded IVF. Our findings offer hope. They suggest that offering structured weight loss support could improve the chance of conceiving naturally, which may avoid the need for IVF treatment. Programmes that help women achieve greater weight losses have the potential to help more women achieve a successful outcome, and should be tested in larger high-quality trials.”
Associate Professor Nerys Astbury, who led the research at the University of Oxford, noted: “The evidence on live birth rates was of very low certainty because many studies did not follow the pregnancies through to birth and report this outcome, which is so important to the patients. While there was no evidence of an increase in pregnancy loss, we need larger, high-quality trials to confirm the effect on live births. It was also interesting that when we restricted the analysis to low-energy diet replacement programmes, which led to greater weight loss, there was an increase in live births, but this needs to be confirmed in larger trials.”
The researchers found a trend towards smaller benefits for natural conception for women with Polycystic Ovary Syndrome (PCOS). However, the researchers are calling for larger, more robust trials that compare weight loss programmes and their link to conception to see which method is most effective and for whom, including women with PCOS.
“This isn’t just about improving pregnancy rates – it’s about improving equity of access to fertility treatment,” Professor Astbury added. “We know that people from more deprived areas and those from certain ethnic backgrounds are more likely to live with obesity. Policymakers should consider whether integrating structured weight loss support into fertility services could improve outcomes for patients, while potentially reducing overall costs by increasing the number of women who conceive naturally.”
Dr Michalopoulou concluded: “For women trying to conceive, every month matters. We need efficient, evidence-based pathways that give them the best chance of success. Our work suggests that for many women with obesity, an intensive supported weight loss programme could help them to conceive naturally or make it possible to access IVF services.”
