Women seeking in vitro fertilization might improve their odds of becoming pregnant if they lose weight, but the magnitude of any advantage wasn't clear, in a new analysis of previous studies.
The benefit of weight loss was mainly seen in the few couples who ultimately achieved pregnancy without assistance, however.
While weight loss interventions appeared to improve the likelihood of spontaneous pregnancy - negating the need for IVF - it was not clear whether they improved the odds of IVF-induced pregnancy, according to the report by Moscho Michalopoulou of the University of Oxford and colleagues in the Annals of Internal Medicine.
Also unclear was whether weight loss improved the odds of a live birth.
Weight loss interventions studied included low-calorie diets, an exercise program accompanied by healthy eating advice, and pharmacotherapy accompanied by diet and physical activity advice – but no single approach seemed better than another.
The 12 randomized trials in the review were small, and the wide variety of methods employed by the various research teams made it hard to compare the results, the authors of the new analysis wrote.
Weight loss did not appear to increase the risk of pregnancy loss, the researchers also found.
Dr. Alan Penzias, an IVF specialist at Beth Israel Deaconess Medical Center/Harvard Medical School in Boston, published an editorial with the study. He notes that “weight reduction among people with overweight or obesity has many known health benefits… (and) some patients may also achieve a desired pregnancy as a consequence of weight loss.”
But in decision-making about IVF, the editorial continues, “we must consider the marked decrease in fertility as age increases… and other factors that weight loss cannot address.”
