Declines in Non-marital Births Among Black Women Between 2004 and 2014: Are Recent Trends the Result of Increases in Contraception?

Non-marital birth rates for women in their twenties began declining in 2008, but the mechanisms driving this decline are not yet well understood. Using a proximate determinants of fertility framework and decomposition techniques, we consider the importance of changes in relationship status, contraceptive use, and other dimensions of deliberate fertility control in understanding trends in the non-marital fertile pregnancy rate between 2004 and 2014. We use data from several cycles of the National Survey of Family Growth to identify relationship and contraceptive use status at the time of conception for pregnancies that resulted or were likely to result in live births (i.e., fertile pregnancies), and focus our analysis on non-Hispanic Black women in their twenties. We find that changes in relationship status and sexual activity did not contribute to the decline in fertile pregnancy rates, nor did changes in the distribution of contraceptive method use. Instead, changing fertile pregnancy rates within contraceptive use categories, including among those who report using no method of contraception, account for the observed trend. Though contraceptive method mix is an insufficient explanation for recent trends, our results suggest that considering the sources of within-method variation in fertile pregnancy rates over time is key to understanding declines in non-marital births, and that some women not using contraception likely engaged in a form of deliberate fertility control not captured by the National Survey of Family Growth.