There is a large literature on the existence of a child penalty for mothers after the birth of a child. There is little discernible effect on fathers' labour incomes, although some studies find that there is a premium. We measure the penalty due to the birth of a first child for both parents for cohorts of young adults after leaving the educational system. Using an event study approach, this paper contributes to the literature by examining the child penalty in France not only in terms of monthly earnings, but also the employment rate, working hours, hourly earnings, and other outcomes. Using on a rich dataset, we estimate child penalty by educational level and for different cohorts. We find evidence of a significant child penalty for mothers: 23% in monthly earnings overall, rising to 35% for those with secondary education only. For the 2010 cohort, we observe the same level of absolute child penalties for mothers, whereas the relative penalty has narrowed. This is due to a decrease in monthly earnings, and more precisely in employment rate of fathers before and after the birth of the child in the aftermath of the 2008 crisis.