Abstract Background A higher osteoarthritis (OA) risk in females is well-documented, but the causes of this sexual dimorphism remain unclear. This study explores whether this disparity arises from sex differences in development or the sex difference in total reproductive costs of gestation and parental care. Method We tested four hypotheses on the effects of gestation and parental care on OA risk using data from the German Aging Survey (DEAS), controlling for age, education, and comorbidities, as appropriate. We analyzed 2,328 men and 2,359 women with children, and 313 men and 319 women without children. We compared OA risk (1) between childless men and women, (2 and 3) within each sex based on parental status, and (4) by the number of children, stratified by sex. We used logistic regression for each test and calculated adjusted 95% confidence intervals and p-values. First test the effect of sex difference in risk development, while the second and third determine the effect of total reproductive costs in each sex, and the fourth examines the dose-dependent effect of reproductive cost in OA risk development. Results No significant difference in OA risk was found between childless men and women (37% and 44%, respectively, CI = -0.035 to 0.602, p = 0.081). However, women with children had a significantly higher OA risk than childless women (51%, and 44%, respectively, CI = 0.004 to 0.483, p = 0.047). Differences in risk between men with and without children were insignificant ( 43%, and 37%, respectively, CI = -0.069 to 0.432, p = 0.156). OA risk increased significantly with the number of children in women (0.10, CI = 0.03 to 0.179, p = 0.006,) but not in men (0.02, CI = -0.058 to 0.091, p = 0.660,) as the previous experiment also suggests. Conclusion Sexual dimorphism in OA risk appears to be driven by the reproductive costs of gestation and parental care. Our findings highlight the need for finer stratification based on reproductive status to better understand sex differences in disease risks.
Das et al. (Tue,) studied this question.