Association Between Sarcopenia Susceptibility and Cesarean Section: A Study Based on National Health and Nutrition Examination Survey (NHANES) and Mendelian Randomization.

Objective: To investigate the relationship between sarcopenia susceptibility and cesarean section (CS) and to assess causality using Mendelian randomization (MR). Methods: Data from 1,316 individuals aged from 20-59 in National Health and Nutrition Examination Survey (NHANES) 2013-2016 were included in the study. The association between sarcopenia and CS was investigated by adjusting for confounders using multivariable linear and logistic regression analysis. Two-sample bidirectional MR was employed to evaluate causal relationships. Genetic data associated with CS (n=462,933) and appendicular lean mass (ALM, n=450,243) were sourced from the largest genome-wide association studies (GWAS). The primary analytical method used was inverse variance-weighted (IVW). Results: Based on the cross-sectional study, the number of CS was positively correlated with sarcopenia across all adjusted models, whereas no such association was observed with vaginal delivery (VD). Subgroup analyses indicated that these associations were primarily evident among premenopausal women. IVW-MR analysis revealed a significant association between sarcopenia and CS (OR=0.989, 95% CI: 0.984 to 0.994, P<0.001), but there was no statistically causal link in reverse (OR=2.100, 95% CI: 0.012 to 364.040, P=0.779). Conclusion: A significant positive correlation and potential causal relationship between sarcopenia susceptibility and CS were identified, which highlighted the need for increased attention to sarcopenia in women with a history or high likelihood of CS, including but not limited to muscle health assessments during prepartum and postpartum periods, along with necessary muscle-strengthening interventions.