An intensive weight-loss intervention prior to conception had no effect on birth rates in women with obesity and unexplained infertility, compared with a standard weight-maintenance program, based on data from nearly 400 women.
Obese women experiencing infertility are often counseled to lose weight before attempting fertility treatments in order to improve outcomes based on epidemiologic evidence of an association between obesity and infertility, but data to support this advice are limited, wrote Richard S. Legro, MD, of Penn State University, Hershey, and colleagues.
The researchers proposed that a more intensive preconception weight loss intervention followed by infertility treatment would be more likely to yield a healthy live birth, compared with a standard weight maintenance intervention.
In an open-label study published in PLOS Medicine, the researchers randomized 379 women at nine academic centers to a standard lifestyle group that followed a weight-maintenance plan focused on physical activity, but not weight loss; or an intensive intervention of diet and medication with a target weight loss of 7%. Both interventions lasted for 16 weeks between July 2015 and July 2018. After the interventions, patients in both groups underwent standardized empiric fertility treatment with three cycles of ovarian stimulation and intrauterine insemination.
The primary outcome was a live birth at 37 weeks’ gestation or later, with no congenital abnormalities and a birth weight between 2,500 g and 4,000 g. Baseline characteristics including age, education level, race, and body mass index (BMI) were similar between the groups.
The incidence of healthy live births was not significantly different between the standard treatment and intensive treatment groups (15.2% vs. 12.2%; P = 0.40) by the final follow-up time of September 2019. However, women in the intensive group had significantly greater weight loss, compared with the standard group (–6.6% vs. –0.3%; P < .001). Women in the intensive group also showed improvements in metabolic health. Notably, the incidence of metabolic syndrome dropped from 53.6% to 49.4% in the standard group, compared with a decrease from 52.8% to 32.2% in the intensive group over the 16-week study period, the researchers wrote.
Gastrointestinal side effects were significantly more common in the intensive group, but these were consistent with documented side effects of the weight loss medication used (Orlistat).
First-trimester pregnancy loss was higher in the intensive group, compared with the standard group (33.3% vs. 23.7%), but the difference was not significant. Most pregnancy complications, including preterm labor, premature rupture of membranes, preeclampsia, and gestational diabetes had nonsignificant improvements in the intensive group, compared with the standard group. Similarly, nonsignificant improvements were noted in the intervention group for intrauterine growth restriction and admission to the neonatal ICU.
Limitations of the study included the relatively small number of pregnancies, which prevented assessment of rare complications in subgroups, and the challenge of matching control interventions, the researchers noted.
However, the results were strengthened by the focus on women with unexplained infertility, the inclusion of a comparison group, and the collection of data on complications after conception, they wrote.
Avenues for future research include interventions of different duration and intensity prior to conception, which may improve outcomes, the researchers said in their discussion of the findings. “A period of weight stabilization and maintenance after a weight-loss intervention prior to commencing infertility therapy is worth exploring,” they noted, but couples eager to conceive may be reluctant to wait for a weight-loss intervention, they added.
“Our findings directly impact current standards of clinical care, where women who are obese with unexplained infertility are to our knowledge routinely counseled to lose weight prior to initiation of infertility treatment,” they concluded.