Teen pregnancy rates are nine times higher among women in the lowest cognitive ability quartile compared to those in the top quartile. This paper presents empirical evidence from the NLSY79 dataset on the relationship between cognitive ability, pregnancy timing, and intention. In addition, a life cycle model is developed and estimated to explore whether variations in wage, marriage, and contraception efficiency by education account for the differences in fertility timing among women with different cognitive abilities. However, these mechanisms only account for half of the correlation between cognitive ability and teen pregnancy. Therefore, I add heterogeneity in contraception efficiency by cognitive ability to bridge this gap. The model reveals that policies that lower contraception costs reduce early pregnancies and enhance women’s welfare. However, the model also shows that teen mothers’ college attendance remains low, as college education is costly for low ability women, even without a teen pregnancy. Finally, I use NLSY97 data to study the decline in teen pregnancies during the ’90s finding a reduction in the cost of contraception and attending college for women in this cohort relative to the NLSY79 cohort.