Over the last decades, the proportion of children born to unmarried mothers has been increasing in Latin America while unmarried cohabitation has become more common. One would expect the former to be a consequence of the latter and that the proportion of children born to unpartnered mothers remained stable or decreased. However, recent research has shown that the proportion of the total fertility rate (TFR) that is attributable to unpartnered women has, in fact, increased. This paper aims at understanding the increase in the share of the TFR attributable to unpartnered women in Latin America. We use census data and the own-children method to measure the evolution of fertility by conjugal union status. We use Poisson regression and a multivariate decomposition technique to examine the respective contributions of changes in the composition of the population and changes in the effects of the characteristics of the population on the changes in fertility. In most countries the proportion of unpartnered women has increased. Their fertility has increased in some countries but decreased in others. In countries where it has decreased, it has done so at a slower pace than the fertility of partnered women, thus increasing the share of fertility that is attributable to unpartnered women.

This research was supported in part by a Standard Research Grant from the Social Sciences and Humanities Research Council of Canada. The participation of Teresa Castro-Martín and Clara Cortina in this research has been funded by the European Union’s Seventh Framework Programme (FP7/2007-2013) under Grant Agreement 320116 for the research project Families And Societies.