Age at First Birth
While much of the research on the second demographic transition focuses on delayed childbearing and the extent to which women are “catching up” at older ages, a primary concern of research on diverging destinies is about the increasing concentration of early childbearing, typically outside of marriage and often outside of stable unions, among less-educated women. As noted in the previous chapter, this focus is motivated by the large body of research demonstrating that this pattern of family formation is negatively associated with the subsequent well-being of both children and mothers. In contrast to the U.S., early childbearing is uncommon in Japan. In 2010, only 1 % of all births were registered to teenage mothers and only 10 % were registered to women age 20-24 (National Institute of Population and Social Security Research 2015).
Nevertheless, it is clear that these early births are concentrated among at the lower end of the educational spectrum. For example, Raymo et al. (2015b) show that nearly all teenage births are to women who failed to complete high school and that about one-fourth of first births to women with a high school education or less occur in the early 20s, compared to only 6 % among university graduates. They also show that the relatively high prevalence of unintended first births among less-educated mothers is partially explained by this relatively high prevalence of early births. Research on trends in educational differences in early childbearing in Japan is limited, but a recent study by Raymo et al. (2015b) finds little evidence of change across cohorts in the concentration of early childbearing among women with a high school education or less. We provide updated evidence on early childbearing in Sect. 4.2.
-  In the U.S., 6 % of births in 2015 were to teenage mothers and 21 % of births were to women age20-24 (http://www.cdc.gov/nchs/data/nvsr/nvsr65/nvsr65_03.pdf, accessed June 3, 2016).