Obesity significantly affects fertility, but evidence linking abdominal obesity and female infertility is limited. Previous studies on BMI and infertility have yielded inconclusive results. Waist circumference (WC), a measure of central obesity, is easily assessed and associated with a variety of health outcomes.
This study uses data from the National Health and Nutrition Examination Survey (NHANES) to examine the potential association between toileting and infertility among U.S. women of childbearing age.
The study involved 3,239 women aged 18 to 45. To investigate the independent association between waist circumference (WC) and female infertility, scientists employed weighted multivariable logistic regression and performed smoothed curve fitting. Subsequently, interaction and subgroup analyzes were conducted as part of the secondary analyses.
Waist circumference (WC) is positively correlated with female infertility, independent of BMI and other factors. In a fully adjusted model, her 1 cm increase in toileting was associated with her 3% increase in infertility risk. When categorizing toilets into her five groups, those in the highest quintile had a 2.64 times higher risk of infertility than those in the lowest quintile.
The relationship between WC and female infertility was nonlinear and had a positive dose-dependent trend. Notably, participants who engaged in moderate recreational activity showed an inverted U-shaped relationship with a tipping point at 113.5 cm. On the other hand, those with insufficient recreational activities showed a J-shaped relationship with a turning point at 103 cm.
Scientists pointed out that: “Our study shows that moderate recreational activity has a protective effect on the risk of latrine-related infertility, especially when the latrine is larger than 113.5 cm.”
Previous studies have shown that moderate to high levels of physical activity significantly reduce the risk of infertility, establishing it as a common protective factor. A prospective cohort study of 3,628 Danish women found a small positive association between moderate physical activity and fertility, independent of BMI.
Furthermore, an inverse association was found between vigorous physical activity and time to pregnancy in all subgroups of women except those who were overweight and obese. These findings suggest that both moderate and vigorous physical activity may enhance fertility, especially in overweight and obese women.
Scientists pointed out that: “Our results support that moderate recreational activity can reduce the risk of infertility associated with increased waist circumference, but insufficient or intense recreational activity can impair pregnancy.”
“Effective waist circumference management strategies and moderate recreational activity are needed to reduce the risk of abdominal obesity and improve reproductive health.”
- Ke J, Feng Y, Chen Z (2023) Association between waist circumference and female infertility in the United States. PLoS ONE 18(12): e0295360. DOI: 10.1371/journal.pone.0295360