Circular causality in daily coparenting processes among first-time parents.

Although coparenting has been widely studied, little is known about the daily processes of coparenting between mothers and fathers in early parenthood. Based on family systems theory and the ecological model of coparenting, we investigated new parents' day-to-day within-family processes of cooperative and tensioned coparenting. Mothers and fathers from 144 Finnish first-time couples completed daily mobile diaries for 7 consecutive days when their firstborn was 4-6 months old. The random-intercept cross-lagged panel model showed three types of within-family processes in daily coparenting, which we named continuity, spread, and shift.