Obese women 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 a recent study.
The University of Oxford-led research, funded by the National Institute for Health and Care Research, analysed 12 international trials involving 1,921 women.
The study also found the interventions increased the odds of any pregnancy – naturally or by IVF by 21%.
But research lead, associate professor Nerys Astbury, said there was a need for “larger, high-quality trials to confirm the effect on live births”.
The researchers said the findings were particularly significant as NHS commissioning bodies across England restrict access to NHS-funded IVF for women with a Body Mass Index (BMI) over 30.
Evidence from a wide range of interventions were used, including diet programmes, exercise and weight loss medications.
On average, women in the intervention groups lost 4kg (9lbs) more than those in the comparison groups.
But the researchers stressed that while the review provided “the clearest picture yet of the benefits for conception”, the effect on the ultimate goal – a healthy baby – “is still unclear”.
Prof Astbury said 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”.
“It was also interesting that when we restricted the analysis to low-energy diet replacement programmes, which lead to greater weight loss, there was an increase in live births, but this needs to be confirmed in larger trials,” she said.
“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 Moscho Michalopoulou, lead author from Oxford’s Nuffield Department of Primary Care Health Sciences, said the findings “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.”