Swedish couples' perceptions of their marital quality when their firstborn was 6 months old and then 4 years later were studied in 2002 and 2006, respectively. The results show that almost half of the 368 responding parents were satisfied with their marital relationship both in 2002 and 2006 as assessed by a modified Dyadic Adjustment Scale. However, a study of the various dimensions showed a significant decrease in marital quality. Housework and child care were perceived as having a greater strain on the relationship between couples who had had additional children during this period. Dyadic Sexuality and Dyadic Cohesion were the most significant predictors of marital quality. Covariates of marital quality in the group with additional children were "partner relation and parenthood perceived as a strain" and "perceived social support." The results emphasize the need for supportive interventions for parents with children aged 0 to 4 years.