Objective
The present study examined trajectories of mothers' and fathers' ratings of the other parent's supportiveness over the first 5 years after the birth of a child to capture the ways in which relationship quality changes for married and unmarried couples during the transition to parenthood.

Design
The sample consisted of 2,172 mothers and fathers, at least one of whom was experiencing a first birth. Parents were assessed at birth and again when their child was 1, 3, and 5 years old. At each assessment they reported on the emotional supportiveness they received from the other parent as well as their relationship status.

Results
Latent growth curve models revealed that, for both mothers and fathers, supportiveness tended to be high at birth and decreased steadily thereafter. Furthermore, perceived supportiveness at 1 year was a better predictor than the same measure at birth in terms of predicting changes in supportiveness over time and whether the couple would break up by the child's fifth birthday. Married couples had the most positive trajectories, with higher levels of supportiveness than dating or nonromantic parents and less decline over time than cohabiting couples. Relationship supportiveness also varied by key demographic variables, including parental race.

Conclusion
Reports of partner supportiveness at birth may not be a good indicator of later support or stability. However, by 1-year postpartum, supportiveness ratings may be more representative of the overall relationship. Family structure is also important in understanding the nature of the transition to parenting among first-time parents.