Lifestyle Intervention Improves Natural Conception but Not Live Births

A structured lifestyle intervention helped women with obesity and infertility achieve more natural pregnancies, but it did not significantly improve live-birth rates compared with usual fertility care, according to findings from the Obesity-Fertility randomized controlled trial.

The academic fertility clinic trial enrolled 127 women aged 18 to 40 years with infertility and obesity, defined as a BMI of at least 30 kg/m², or at least 27 kg/m² among participants with polycystic ovary syndrome. Women considered unlikely to conceive naturally were excluded.

Participants were randomized to either usual fertility care or a 6-month lifestyle intervention before fertility treatment was added. The intervention included individualized follow-up with a dietician and kinesiologist, along with group sessions.

At 6 months, women in the intervention group had greater reductions in weight and waist circumference than those receiving usual care. Mean weight loss was 3.21% in the intervention group versus 0.40% in the control group, and waist circumference declined by 2.62 cm versus 0.23 cm, respectively.

The primary outcome, live birth from a pregnancy conceived within 18 months of randomization, occurred in 44.4% of women in the intervention group and 35.9% of those in the control group. This difference did not reach statistical significance. Clinical pregnancy rates were also numerically higher with the intervention, at 52.4% versus 37.5%, but again did not meet statistical significance.

A notable difference emerged in natural pregnancy rates. Women assigned to the lifestyle intervention were more than twice as likely to conceive naturally as those receiving usual care, with rates of 27.0% versus 12.5%.

The findings suggest that delaying fertility treatment for a structured lifestyle program may not meaningfully increase live births within 18 months, but it could reduce reliance on assisted reproduction for some patients. That distinction may be clinically important, given the financial, emotional, and physical burdens associated with fertility treatment.

The authors concluded that while the intervention did not significantly improve the overall rate of pregnancies leading to live birth, it significantly increased natural pregnancies in this population.