And Baby Makes Four: Predictors of Attachment Security among Preschool-Age Firstborns during the Transition to Siblinghood.

Examined first-born preschoolers' adjustment to siblinghood, as indexed by security of attachment, in 194 2-parent families. Security of firstborn attachment decreased significantly after a secondborn's birth, but the decrease was smaller among firstborn under 24 months than among 2- to 5-year-olds. Mothers' marital harmony, affective involvement, and psychiatric symptoms were also found to predict firstborn security. (HTH)