The differences in teenage fertility by education level in Latin America have been researched extensively. However, little is known about the evolution of the educational disparities in the timing of motherhood throughout the fertility transition more broadly in the region. Using census data I estimate the first-birth age-specific probabilities, disaggregated by education level, for cohorts of women born between 1945 and 1980 in three countries of the Andean Region: Ecuador, Peru and Colombia. In all countries, educational expansion was accompanied by the increasing rates of first birth before age 19 among women with below completed higher education. This increase was most pronounced among women who drop out of secondary school. Concurrently, the first-birth rates at age 20-29 were decreasing for women who achieved higher education; an increase in the rates above age 30 among them is also observed. These processes led to a substantial divergence in the first-birth timing between the educational groups throughout the fertility transition. These results are robust to alternative education level classification and are not driven by the increasing selectivity of women with few years of schooling. I provide evidence that women in lower socioeconomic strata have not benefited equally from the expansion of the educational systems, increasing access to contraception and labour market opportunities as women in higher socioeconomic groups. This paper argues that there is a need for policies focusing on creating conditions which encourage secondary school completion and policies addressing the underlying causes of the reproductive polarization in these three countries.