The Earned Income Tax Credit (EITC) is one of the largest anti-poverty programs in the US, providing low-income households with a wage subsidy that varies by income level and household size. The credit increases substantially upon the birth of a household's first child, resulting in stronger incentives for labor market participation among households in the "phase-in" region of the credit, most of which are headed by single mothers. If mothers make birth spacing decisions by trading off the health costs of small birth intervals against their desire to limit time out of the labor market, the EITC may then decrease spacing among single mothers. 

In order to test my hypothesis, I use a novel identification strategy that takes advantage of the cut-off in first child's birth month around the end of the tax year. I also use variation in simulated credit amounts and maternal marital status as sources of variation. Using three separate large and nationally representative datasets and differing definitions of birth spacing, I present robust evidence that both receipt and amount of the EITC decreases birth spacing among low-education, single mothers. I find slightly negative or zero effects on completed fertility. These results are in line with the theoretical predictions. 

My research is important in light of recent evidence that small birth intervals deplete maternal nutrition for the younger child. Economic research shows that nutrition in utero plays a keys role in determining later life outcomes. Despite medical guidelines on spacing, I show that a relatively large fraction of births to low-education mothers are still spaced too closely.