Table 1_Parental depressive symptoms and shared reading practices among preschool children in western China: cross-sectional study.docx

Piecewise regression identified a significant estimated breakpoint at CES-D score = 19.0 (95% CI: 11.9–26.1), below this threshold the slope was steeper (β = –0.085) than above (β = –0.051). Natural spline analysis confirmed non-linearity (P = 0.026) and located the point of maximum curvature at CES-D score = 10.9, indicating the most rapid change in slope occurred at subclinical symptom levels. The association was consistent across all subgroups (after Bonferroni correction).</p>Conclusions<p>Parental depressive symptoms are negatively associated with shared reading in a non-linear, breakpoint-dependent manner.

Even subclinical symptoms (CES-D score≈ 11) are associated with steeper declines, while the association attenuates at higher levels (CES-D score ≈ 19). Interventions targeting parental mental health, especially at subclinical to moderate symptom levels, may help preserve high-quality home literacy environments.</p>