La natalidad sigue cayendo en España y sólo crece en dos comunidades

A second approach focuses on the opportunity cost of having children, especially for women. Since raising children requires parental (and especially maternal) time, fertility is more costly for higher-income mothers, who are therefore expected to have fewer children (e.g., Kravdal 1992). This is related to the literature that demonstrates a ‘motherhood wage penalty’, with postponement providing considerable earnings returns for higher educated women or those in professional occupations (Van Bavel 2010; Begall and Mills 2012). Miller (2010) demonstrated for example, that a year of delayed motherhood increased women’s earnings by 9 %, their work experience by 6 % and average wage rates by 3 %. Others have extended Becker’s static model by setting up dynamic economic models of the optimal timing of first birth (mostly focusing on women), based on the minimization of opportunity costs of childbearing, ‘wage penalty’ and income loss (Happel et al. 1984; Cigno and Ermisch 1989). They theorized and demonstrated that the higher the accumulation of human capital during education or the higher the returns to education, the later the transition to motherhood. Gustafsson (2001, 2002) demonstrated that women’s career planning was the main explanation for postponement, a finding replicated in more recent studies in Sweden (Gustafsson 2005), the U.K. (Kneale and Joshi 2008), Ireland (O’Donoghue et al. 2011), the U.S. (Amuedo-Dorantes and Kimmel 2005; Miller 2010) and Italy (Rondinelli et al. 2010).

A similar approach has been adopted by the rich body literature that focuses on the relationship between education and labor market trajectories and the timing of first birth. The argument is that due to the accumulation of human capital, women with higher levels of education are more likely to pursue careers and increase their earning power. This likewise releases them from the pressure to get married and have a child for economic reasons. As the opportunity costs of childbearing and childrearing increase with human capital, highly educated women are more likely to postpone marriage and births. An important critique of this approach has been put forth by Oppenheimer (1994), who argues that highly educated women are more likely to find partners who are highly educated as well. This in turn operates as an incentive for women (because they can further pool economic resources) to enter into a union and subsequently have children once they complete their education. In line with Oppenheimer’s approach, other studies find that the higher educated are more likely to have a(nother) child or have overall, higher fertility (Mencarini and Tanturri 2006; Mills et al. 2008), since: (i) they are also likely have a partner with higher education and therefore a higher wage (Behrman and Rosenzweig 2002); (ii) they have stronger bargaining power within the couple, leading to a more equal division of domestic labor; and, (iii) they can outsource housework. Although higher educated women have their first child later than their lower educated counterparts, some studies (Sobotka 2004; Kravdal and Rindfuss 2008) have highlighted that the higher educated are also more likely to recuperate at a later age. Or in other words, that the cumulative impact of late motherhood on higher-order birth rates (i.e., second or third births) disappears.

The results linking education to fertility are, however, mixed, with recent empirical results instead showing a non-relevant association between education and fertility (e.g., Skirbekk 2008). Using a natural experiment approach on school entry policies in California and Texas (which should be able to unravel causality), McCrary and Royer (2011) find that education does not significantly impact fertility. Several studies also find a strong inverse relationship between educational attainment and the timing of first births in different countries (Rindfuss et al. 1980, 1996; Martin 2000 for the U.S.; Joshi 2002 for U.K.; Lappegard 2002 for Norway; Meron and Widmer 2002 for France; Noguera et al. 2003 for Spain).