This dissertation centers on two themes. First: how do public policies affect the incentives of mothers to participate in the labor market? And second: how do these maternal employment incentives and economic opportunities impact the health of children? In the first chapter, I focus on the first theme, and identify the impact of a large means-tested preschool program, Head Start, on the labor supply of mothers. This chapter uses a discontinuity in grant writing assistance in the first year of the Head Start program to identify impacts on the work and welfare usage of mothers. Using restricted Decennial Census and administrative AFDC data I find that Head Start decreases employment rates and hours worked per week for single mothers. I also find a suggestive increase in welfare receipt for single mothers which is confirmed by an increase in the share of administrative welfare case-files that are single mother households. For all mothers combined there are no significant changes in work or welfare use. I also estimate long-run impacts, 10 years after a woman's child was eligible for Head Start. I find large and persistent declines in work for both non- white mothers and single mothers, accompanied by increase in public assistance income and return to school. I argue that this is consistent with the 1960's era Head Start program's focus on encouraging quality parenting, parent participation and helping families access all benefits for which they were eligible. In the second chapter, my coauthor, Gaetano Basso, and I examine the impacts of California's Paid Family Leave program on the health of infants. One goal of the policy was to make it easier for working mothers to take maternity leave, and encourage their return to work. Pervious research has confirmed that the policy resulted in longer maternity leave durations, which we theorize may impact infant health. We measure health using the full census of child hospitalizations in California. The potential policy implications are of great interest both because of the high costs of health care in the U.S., and to better evaluate a potential benefit of the family leave policy overlooked by the existing literature. Our results suggest a decline in infant admissions, which is concentrated among those causes that are potentially affected by closer childcare (and to a lesser extent breastfeeding). Other admissions that are unlikely to be affected by parental leave do not exhibit the same pattern. In the third chapter, I examine the mechanisms through which the business cycle influences child health and development. There is a growing literature which finds large consequences of conditions in utero for health and success. Using a large survey of births covering the period 1990-2014, I use a state-year panel fixed effects model to examine the relationship between the business cycle and breastfeeding, stress while in-utero, and cigarette and alcohol consumption before, during and after pregnancy. I find suggestive evidence that the share of births that are unplanned rise with the unemployment rate. I also find that pregnant women are more likely to experience economic stress in times of high unemployment - but that this is primarily through an increase in the probability that their husband or partner loses their job. The pregnant woman's own employment is unaffected. Breastfeeding shows mixed results, but for the sample of states that appear most frequently in the data, both initiation and duration increases with the unemployment rate.