The Impact of Fertility on Mothers' Labour Supply in Australia: Evidence from Exogenous Variation in Family Size

This paper estimates the impact of fertility on mothers’ labour supply in Australia, using exogenous variation in family size generated by twin births and the gender mix of siblings. Results show that having more than one child decreases labour market participation by 15.5 percentage points and hours worked by around 6 hours per week. Having more than two children reduces labour market participation by between 12 and 20 percentage points and hours worked by between 3 and 8 hours a week, depending on the instrument used. Interestingly, fathers also reduce both their labour market participation (by 10 percentage points) and their number of hours worked per week (by 4 hours) when having more than one child. Compared with the results obtained with the same methodology for other countries, the effects for Australia are large, which partly reflects the constraints on public childcare and the lack of a national paid parental leave scheme prior to 2011.