The paper studies the relationship between cognitive ability, education outcomes, wages, and fertility timing, focusing on how cognitive ability influences fertility decisions. First, the paper presents empirical evidence on the relationship between cognitive ability, early pregnancies, and pregnancy intention using NLSY79 data. Second, I build and estimate a heterogeneous life-cycle model to quantify the importance of cognitive ability, wages, marriage, and education outcomes on women’s fertility and see if the relationship between cognitive ability, education, and wages explains the relationship between cognitive ability and fertility, I find that they can not do it. Next, I use the model to analyze how decreasing contraception costs affect early pregnancies and women’s educational outcomes once we account for cognitive ability. Finally, I study the mechanism behind the decline in teen pregnancies during the ’90s.