Moderate and increased physical activity is not detrimental to live birth rates among women with unexplained infertility and obesity

To determine if moderate physical activity is associated with live birth rates in women with unexplained infertility and obesity. Secondary analysis of the Improving Reproductive Fitness through Pretreatment with Lifestyle Modification in Obese Women with Unexplained Infertility trial. US fertility centers, 2015–2019. A total of 379 women participated in Improving Reproductive Fitness through Pretreatment with Lifestyle Modification in Obese Women with Unexplained Infertility trial, a lifestyle modification program with increased physical activity (phase I, 16 weeks) and up to three cycles of clomiphene citrate treatment and intrauterine insemination (phase II). Participants were instructed to add 500 steps/day weekly until a maximum of 10,000 steps/day was reached and maintained. Participants were stratified as active (top third, N = 125) and less active (lower third, N = 125) on the basis of the average number of steps per day recorded using a FitBit activity tracker. Live birth rate. Active participants were more physically active at the time of enrollment than less active participants (average baseline steps per day, 8,708 [7,079–10,000] vs. 4,695 [3,844–5,811]; P ≤ 0.001) and were more likely to reach 10,000 steps/day than less active participants (average steps per day, 10,526 [9,481–11,810] vs. 6,442 [4,644–7,747]; P ≤ 0.001), although both groups increased their average steps per day by a similar amount (1,818 vs.1,747; P = 0.57). There was no difference in live birth rates (24/125 [19.2%] vs. 25/125 [20%]; P = 0.87) between active and less active participants nor were there differences in clinical pregnancy rates (P = 0.45) or miscarriage rates (P = 0.49) between the two groups. Active participants were more likely to achieve the physical activity goal, although this was not associated with benefit or harm with respect to live birth. ClinicalTrials.gov (NCT02432209), first posted: May 4, 2015.