Physical activity does not affect birth outcomes in women with obesity
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Increased physical activity before and during fertility treatment was associated with improved metabolic measures but did not impact birth outcomes among women with obesity, researchers reported.
“Women with infertility often worry that physical activity will prevent conception or increase their risk of miscarriage,” author Wendy S. Vitek, MD, associate professor at the University of Rochester Medical Center, told Healio. “We can reassure women with obesity and infertility that moderate physical activity while trying to conceive is not detrimental to conception or live birth.”
Researchers sought to determine the effect of a pretreatment intensive lifestyle modification on live birth among women with obesity and infertility.
The Improving Reproductive Fitness through Pretreatment with Lifestyle Modification in Obese Women with Unexplained Fertility (FIT-PLESE) trial involved caloric restriction, orlistat and moderate physical activity, including the addition of 500 steps a day each week until the goal of 10,000 steps a day was reached and maintained.
said Vitek.
FIT-PLESE studied the relationship between lifestyle change and live birth among women with unexplained fertility undergoing ovulation induction and insemination. It has not been published yet but will be soon, according to Vitek, who was part of a team conducting a secondary analysis of its results.
“Women with obesity are more likely to experience a longer time to pregnancy, ovulatory dysfunction, lower conception rates with infertility treatment from ovulation induction and IVF, an increased chance of pregnancy loss with conception and higher rates of pregnancy complications, such as pre‐eclampsia and gestational diabetes, resulting in increased risk of maternal and infant morbidity and mortality,” Vitek said.
Participants were stratified as active (top third, n = 125) and less active (lower third, n = 125) based on the average number of steps a day recorded by a FitBit pedometer before and after conception.
“We were interested in examining active minutes — continuous moderate-to-intense activity based on heart rate for 10 or more minutes per day — but this metric was not recorded in the dataset,” Vitek said.
The active participants had more baseline steps (8,708 vs. 4,695; P .001) and more steps per day at the end of the preconception phase (10,526 vs. 6,442; P .001) than the less active participants. Also, 72.2% of the active participants maintained a high activity level after conception.
The results of the trial, presented at the ASRM Scientific Congress & Expo, showed that the active participants had lower Hgb A1C (5.4 vs. 5.5; P = .01) and triglyceride (115 vs. 125; P = .004) levels than the less active participants, but there was no difference in the number of treatment cycles (P = .45), dose of clomiphene (P = .09), or rates of conception (P = .49), clinical pregnancy (P = .45), miscarriage (P = .49), live birth (P = .84) or good live birth outcome (P = .7).
“We thought the participants who were randomized to the intensive lifestyle modification, which included coaching, would have more ‘active participants’ (top third based on average step counts/day) and that there would be fewer ‘active participants’ in the standard intervention,” Vitek said. “We saw a similar number of ‘active participants’ in both arms, which was surprising.”
The researchers also were surprised there was no difference in any outcomes such as number of cycles or time to pregnancy, dose of clomiphene, rate of conception, rate of clinical pregnancy, rate of miscarriage, rate of live birth or rate of good birth outcome between active and less active participants.
“There was a non-significant trend toward lower miscarriage in the active group compared to the inactive group, but the number of miscarriages was overall low so there may be insufficient power to detect a small difference between the groups,” Vitek said.
The researchers concluded that the active participants were more metabolically fit, but there was no relationship between higher activity levels and the birth outcomes they measured.