HELSINKI – A 6-month lifestyle intervention was associated with an increased natural conception rate in infertile anovulatory obese women, compared with infertile ovulatory obese women, although the rate of vaginal births of healthy singletons did not differ between the groups, according to subgroup analyses of the Lifestyle randomized controlled trial.
The findings, which confirm those in the overall study population and are likely explained by the beneficial effects of weight loss on the resumption of ovulation, have implications for managing obese women who are experiencing infertility, according to Anne van Oers, MD, of the University of Groningen (the Netherlands).
The Lifestyle trial – a multicenter study conducted in the Netherlands and published in 2016 – involved a 6-month lifestyle intervention preceding fertility treatment in obese infertile women. The intervention had no effect on the rate of vaginal births of healthy term singletons within 24 months versus immediate fertility treatment (relative risk, 0.77), although natural conceptions with an ongoing pregnancy did occur more often in the lifestyle intervention group (relative risk, 1.6).
For that study, conducted from 2009 to 2012, the investigators randomized 577 obese infertile women to either the 6-month lifestyle intervention followed by 18 months of infertility treatment or to immediate fertility treatment. Weight loss was 4.4 kg in the intervention group and 1.1 kg in the control group, Dr. van Oers said at the annual meeting of the European Society of Human Reproduction and Embryology.
For the subgroup analyses, the investigators focused on six groups based on age (those 36 years and older and those under age 36), ovulation status (those who were anovulatory and those who were ovulatory), and body mass index (those with a body-mass index (BMI) of 35 kg/m2 or greater and those with BMI under 35).
In the 564 women who completed follow-up, only the rate of natural conception was improved by the preconception lifestyle intervention: This was true in most of the subgroups, but was most pronounced among anovulatory women (28% vs. 11.4% in ovulatory women who received the intervention), she said.
Obese women are known to be at increased risk of infertility and are less likely than nonobese women to conceive after fertility treatment. In one prior study, ovulating subfertile women with a BMI of 29 kg/m2 or higher had a 4% lower pregnancy rate per kg/m2 increase per year, compared with ovulatory subfertile women with a BMI below 29, Dr. van Oers noted.
Although the current findings are limited by the nature of the subgroup analyses – the main study was not powered on analyses of subgroups or interaction tests – the findings do suggest a benefit of lifestyle intervention in some women, she noted.
“Our findings that lifestyle intervention in obese women more often leads to natural conception, specifically in anovulatory women, should be used in their counseling before fertility treatment and could reasonably be offered as first-line treatment for anovulation in obese women,” she said in a written statement.
Of note, 22% of the women in the main study were unable to adhere to the lifestyle intervention despite intensive coaching, according to the study’s project leader, Annemieke Hoek, MD, PhD, also from the University of Groningen.
The women who did not complete the program were significantly less likely to become pregnant, and those who did complete the program were more likely to conceive naturally, compared with the women in the control group who received immediate fertility treatment, Dr. Hoek said, noting that, again, this effect was most pronounced in anovulatory women.
Dr. van Oers and Dr. Hoek reported having no financial disclosures.