I. INTRODUCTION: UNDERSTANDING THE TRANSITION TO SIBLINGHOOD FROM A DEVELOPMENTAL PSYCHOPATHOLOGY AND ECOLOGICAL SYSTEMS PERSPECTIVE.

Abstract

The birth of an infant sibling is a common occurrence in the lives of many toddler and preschool children. Early childhood is also a time for the emergence of disruptive behavior problems that may set the stage for later problem behaviors. The current study examined individual differences in young children’s behavioral and emotional adjustment after the birth of a sibling in an effort to uncover developmental trajectories reflecting sudden and persistent change (maladaptation), adjustment and adaptation (resilience), gradual linear increases, and no change (stability and continuity). Growth mixture modeling (GMM) was conducted with a sample of 241 families expecting their second child using a longitudinal research design across the first year after the sibling’s birth (prenatal, 1, 4 8 and 12 months) on seven syndrome scales of the Child Behavior Checklist (CBCL 1.5–5:(Achenbach & Rescorla, 2000): aggression, attention problems, anxiety/depression, emotional reactivity, withdrawal, somatic complaints, and sleep problems. For all scales, multiple classes describing different trajectory patterns emerged that reflected predominantly intercept differences; children high on problem behavior after the birth were those high before the birth. There was no evidence of a sudden, persistent maladaptive response indicating children underwent a developmental crisis for any of the problem behaviors examined. Most children were low on all problem behaviors examined and showed little change or actually declined in problem behaviors over time, although some children did experience more pronounced changes in the borderline clinical or clinical range. Only in the case of aggressive behavior was there evidence of an Adjustment and Adaptation Response showing a sudden change (prenatal to 1 month) that subsided by 4 months, suggesting that some young children react to stressful life events but adapt quickly to these changing circumstances. Further, children’s withdrawal revealed a curvilinear, quadratic path, suggesting children both increased and decreased in their withdrawal over time. Guided by a developmental ecological systems framework, we employed data mining procedures to uncover the child, parent, and family variables that best discriminated the different trajectory classes and found that children’s temperament, coparenting, parental self-efficacy, and parent-child attachment relationships were prominent in predicting children’s adjustment after the birth of an infant sibling. Finally, when trajectory classes were used to predict sibling relationship quality at 12 months, children high on aggression, attention problems, and emotional reactivity in the year after the birth engaged in more conflict and less positive involvement with the infant sibling at the end of the first year.