Association between physical activity and infertility: a comprehensive systematic review and meta-analysis

Area of Science:

• Reproductive Health
• Epidemiology
• Preventive Medicine

Background:

• Physical activity (PA) is hypothesized to protect against infertility by influencing the hypothalamic-pituitary-gonadal axis, immune function, and hormone levels.
• The precise impact of PA on infertility risk, however, remains incompletely understood.
• This study systematically reviewed existing evidence to clarify the preventive role of PA in infertility.

Purpose of the Study:

• To conduct a systematic review and meta-analysis to determine the preventive effects of physical activity on infertility.
• To assess the relationship between different levels of physical activity and the risk of infertility.
• To evaluate PA as a potential protective factor against infertility in a large population.

Main Methods:

• A systematic search of major databases (PubMed, Cochrane Library, EMBASE, CINAHL) was performed for relevant epidemiologic studies.
• Studies published in English before April 11, 2022, were included, adhering to PRISMA guidelines.
• Study quality was assessed using the Newcastle-Ottawa Scale, with a registered protocol on PROSPERO (ID: CRD42020143344).

Main Results:

• The analysis included 10 studies (6 cohort, 4 case-control) with 708,965 subjects and 12,580 infertility cases.
• High PA levels were associated with a reduced risk of infertility (cumulative RR=0.59, 95% CI 0.49-0.71) compared to low PA levels.
• Moderate PA also showed a protective effect (RR=0.54, 95% CI 0.38-0.77), though high PA slightly increased risk versus moderate PA (RR=1.31, 95% CI 1.08-1.59).

Conclusions:

• A significant inverse relationship exists between PA levels and infertility risk.
• Moderate-to-high PA levels are identified as a common protective factor significantly reducing overall infertility risk.
• Further research is needed to define optimal PA frequency, dosage, and duration for infertility prevention.