The U-curve associations of birth interval with prevalence of osteoarthritis in postmenopausal women.

BACKGROUND

To explore associations of birth interval, age at first birth (AFB), age at last birth (ALB) with prevalence of osteoarthritis (OA) in United States (U.S.) postmenopausal women with two deliveries.

METHODS

Cross-sectional analysis of 3088 postmenopausal women with two deliveries from the National Health and Nutrition Examination Survey (1999-2018). Weighted multivariable logistic regression, subgroup analysis and restricted cubic spline (RCS) models were used to examine association of reproductive factors (birth interval, AFB and ALB) with OA risk.

RESULTS

The prevalence of OA was 30.6%. According to RCS, we found the U-shaped relationships were observed between AFB, ALB, birth interval and risk or OA in postmenopausal women. 24-25 years for AFB, 25-30 years for ALB, and 4-6 years for birth interval were associated with lowest OA risk. These associations persisted across various subgroups.

CONCLUSIONS

AFB, ALB and birth interval shown the U-shaped associations with OA prevalence in postmenopausal women with two deliveries. These findings highlight the potential long-term impacts of reproductive history on musculoskeletal health and may inform strategies for OA prevention in U.S. postmenopausal women.