Data from an Australian national household survey has been used to analyse adults’ mental health after having children. The survey followed 20,000 Australians for up to 16 years. The results show that having a first child increases adults’ time pressure as they are introduced to the role of parenting. However, having more children further increases the demands on parents. Having a second child doubles the time pressure on parents. The effects of which were found to be larger for mothers, therefore widening the gap between mothers and fathers. The study suggests mothers’ mental health improves with their first child, immediately after the birth, and this remains stable for the next few years. However, mothers’ mental health sees a sharp decline, and remains low, after having a second child. Fathers’ also experience a decline, but this plateaus over time.