Impact of Sitting Time and Vigorous Leisure-Time Activity on Infertility in Reproductive age U.S. Women

Objective Our aim was to explore the relationship between daily sitting time and infertility in U.S. women of reproductive age, and to assess how this relationship is influenced by vigorous leisure-time physical activity. Methods We analyzed data from 3,065 women aged 18–44 years, drawn from the National Health and Nutrition Examination Survey (NHANES) for the years 2013–2018. We assessed daily sitting time and participation in vigorous leisure-time physical activity. Using logistic regression models, we estimated the odds ratios (ORs) for the association between daily sitting time and self-reported infertility. Additionally, we explored the interaction between daily sitting time and vigorous leisure-time physical activity was examined on both multiplicative and additive scales to understand how physical activity might modify the impact of sitting time on infertility. Results Daily sitting time exceeding 4 hours was linked to an increased risk of infertility, with an OR of 1.59 (95% CI: 1.07–2.36). This risk was notably significant among women who did not engage in vigorous leisure-time physical activity, with an OR of 1.57 (95% CI: 1.08–2.28), compared to those sitting less than 4 hours daily. Moreover, the relative excess risk due to the interaction between prolonged sitting and lack of vigorous physical activity was -1.20 (95% CI: -2.33, -0.07), indicating a potential mitigating effect of vigorous activity on the negative impact of extended sitting on fertility. Conclusion Extended daily sitting time is linked to a heightened risk of infertility in women of reproductive age, especially in those who do not participate in vigorous leisure-time physical activity.