This thesis contributes to a better understanding of the labour supply of women, and more specifically mothers, in Switzerland. It begins in Chapter 1 by highlighting the difficulties encountered by parents, and mainly women, in balancing work and family life. Women often leave the labour market or reduce their work time percentage after bearing a child. The consequences of these interruptions or reductions in the participation rate are significant on their career and its development, as well as on the wage rate. Highly-educated women are the most affected by the loss of professional skills, experience and wages. According to estimates made in Chapter 2, the wage loss caused by a career break is almost one million Swiss francs over the entire career for these women. Women should therefore care more about the continuity of their professional careers to avoid ending up in a precarious financial situation, especially in the event of a divorce or upon retirement. Chapter 3 discusses factors that can influence women's labour supply and shows that childcare services are among the most important factors. While most of the studies carried out so far agree on the negative effect of the cost of childcare services on the mothers’ labour supply, the magnitude of the effects varies considerably across studies. Chapter 4 attempts to understand why thanks to a meta-analysis. In Chapter 5, we estimate precisely how the availability and the cost of the childcare centres influence the labour supply of mothers in Switzerland. The lack of childcare slots turns out to be the major issue for mothers and influences both the decision to work and the quantity of labour. We estimate that the creation of a slot would increase the labor supply of mothers by a full-time equivalent. The cost of childcare “only” influences the quantity of work and is conditional on having a slot. An estimate of the cost for the State of increasing the supply of childcare centres shows that the additional tax revenue more than covers the cost of these new slots. It is therefore possible to reach a win-win situation for both families and the society. For the economy, the consequences of a lower participation of women in the labour market are also numerous. It implies a suboptimal use of the talent pool, a loss of productive capacity and a lower return on investment in education. It also weakens the pension and social assistance system, already undermined by an aging population. It is therefore necessary for the State to intervene by creating adequate financial and institutional conditions to ensure a better work and family life balance.