In 2007 abortion was legalized in the Federal District of Mexico, making it the largest jurisdiction in Latin America, outside of Cuba, to allow women to have abortions on request during the first trimester of pregnancy. While the implications of the law for women's health and maternal mortality have been investigated, its potential association with fertility behavior has yet to be assessed. We examine metropolitan‐area differences in overall and parity‐specific childbearing, as well as the age pattern of childbearing between 2000 and 2010 to identify the contribution of abortion legalization to fertility in Mexico. Our statistical specification applies difference‐in‐difference regression methods that control for concomitant changes in other socioeconomic predictors of fertility to assess the differential influence of the law across age groups. In addition, we account for prior fertility levels and change to better separate the effect of the law from preceding trends. Overall, the evidence suggests a systematic association between abortion legalization and fertility. The law appears to have contributed to lower fertility in Mexico City compared to other metropolitan areas and prior trends. The influence is mostly visible among women aged 20–34 in connection with the transition to first and second child, with limited impact on teenage fertility. There is some evidence that its effect might be diffusing to the Greater Mexico City Metropolitan area.