Newborn Siblings and Existing Adolescent Development: Examination of the Transition to Siblinghood

Adolescents’ healthy, holistic development is shaped by family processes. The arrival of a newborn sibling is a brief, intense transition to siblinghood (TTS) that reorganizes roles and attention; yet short-term adolescent outcomes in this window are seldom examined, and findings remain inconsistent. Using two-wave national data on Chinese junior secondary students ( N = 8,896), we estimated lagged models adjusting baseline outcomes and tested maternal and paternal support as indirect pathways. Relative to no TTS, both first-time and additional TTS were associated with higher depressive symptoms and lower academic performance, while the cognitive association appeared primarily for first-time TTS. Pooled interaction tests showed no slope difference for depression or academics, and indirect paths via maternal but not paternal support partially accounted for several links. Findings highlight short-term challenges around sibling birth and suggest that strengthening everyday parental support may help adolescents navigate TTS.