This study paper investigates the relation between women and men's life stages in Denmark, and their time allocation in paid work, household work, childcare, and leisure time, and, in particular, how this allocation changes when moving from one stage to another stage. The study uses a new Danish panel dataset merged with Danish administrative register data, which allows for analyzing the impact of individual endogenous characteristics of the respondents, such as preferences for doing specific activities. It has been found that the labor supply of fathers of preschool children is not different from that of young men without children, while there is a negative correlation between mothers of preschool children and young women's labor supply. In comparing fathers and mothers of school children with those of preschool children, the study finds a positive correlation in both genders' labor supply. However, fixed effects estimations do not result in a reduction in mothers, nor in fathers, to preschool children's labor supply, indicating that there are some inborn characteristics for the other life-stage changes, which are not revealed by doing ordinary cross-sectional analyses.