Toward a Unified Theory: Understanding the Associations of Earnings with Marriages and Births

Christina M. Gibson-Davis, Duke University

This study examines the conventional assumption that marriage and fertility are interconnected by comparing the effects of earnings on marriage to the effects of earnings on fertility. Data come from the Survey of Income and Program Participation, a nationally representative sample of U.S. adults. Change in male earnings was more strongly related to marriage than to fertility, as earnings were positively correlated with marriage but had no effect on childbearing. The positive association between male earnings and marriage held only for childless men, suggesting a moderating role of childbearing. Females were also more sensitive to changes in earnings for marital than for fertility decisions. Effects differed from those of men, as female earnings had no significant correlation with marriage, but were negatively correlated with fertility. The findings confirm that earnings havea differential effect on marriage than on fertility and suggest that models should recognize the disconnect between the two.