Women living with obesity 47 per cent more likely to conceive naturally after losing weight, study finds

Women with living obesity who take part in structured weight loss programmes before beginning IVF are 47 per cent more likely to conceive naturally, according to the largest review of evidence to date.

The University of Oxford-led analysis, funded by the National Institute for Health and Care Research, examined 12 international clinical trials involving 1,921 women. It found that weight loss support also increased the likelihood of any pregnancy, natural or via IVF, by 21 per cent. On average, women in the intervention groups lost 4kg more than those receiving minimal or no support.

Published in the Annals of Internal Medicine, the study comes as many NHS commissioning bodies in England restrict access to publicly funded IVF for women with a Body Mass Index above 30. Researchers say that structured weight loss support could not only help more women meet eligibility criteria but also reduce the need for fertility treatment altogether.

Lead author Dr Moscho Michalopoulou, from Oxford’s Nuffield Department of Primary Care Health Sciences, said: “Women with obesity face higher rates of infertility and may be excluded from NHS-funded IVF. Our findings suggest structured support could improve the chance of conceiving naturally and help more women achieve a successful outcome.”

The review included diet and exercise programmes as well as medications such as orlistat and older GLP-1 receptor agonists, the drug class now including Ozempic and Wegovy. The researchers noted that while evidence for conception rates was strong, the impact on live births remains uncertain due to limited follow-up in many trials.

Associate Professor Nerys Astbury, who led the research, said integrating structured weight loss into fertility services could improve access and outcomes, particularly for women from more deprived areas and certain ethnic backgrounds, who are more likely to be living with obesity.