The Mediating Role of Inner Strength in the Relationship Between Biological Factors and Depressive Symptoms

Background: Depression is a significant public health concern, with working mothers at greater risk due to combined biological and psychosocial stressors. Recent evidence suggests that inner strength may play a mediating role in the link between biological risks and depression. Objectives: The primary objective was to determine whether inner strength mediates the relationship between biological risk factors (hormonal fluctuations, smoking, alcohol use, family psychiatric history, and physical diseases) and depressive symptoms among Chinese working mothers. A secondary objective was to assess the prevalence of depressive symptoms in this population, measured with the OI-Depression subscale (Outcome Inventory-21). Methods: A cross-sectional online survey was conducted with 330 Chinese working mothers aged 30–45 years, using validated instruments to measure depression, inner strength, and parental stress. Mediation analysis evaluated the indirect effect of inner strength, while covariate-adjusted regression analyses explored associated factors. Results: Biological risk factors showed a significant direct effect (β = 0.584, p < 0.001) and an indirect effect through inner strength (indirect effect = 0.623, 95% CI [0.294, 0.962]. The Sobel test indicated that the indirect effect of biological risk factors on depressive symptoms through inner strength was statistically significant (z = 3.67, p < 0.001). The prevalence of clinically significant depressive symptoms was 38.2%. Conclusions: Biological factors significantly contribute to depressive symptoms, but inner strength partially mediates this relationship, suggesting that interventions to enhance inner strength may help reduce depression risk in working mothers. Further research should investigate strategies to build inner resilience in this population.