A more plausible explanation is the one put forward by Stanford law professor Ralph Richard Banks in his book “Is Marriage for White People?” Having a spouse, Mr. Banks speculates, may be what matters most in a woman’s decision to seek an abortion. “A single woman with an unplanned pregnancy is about twice as likely as a married woman to abort,” he writes. “Black women thus may have so many more abortions than other groups in part because they are so much less likely to be married.”

The irony, he adds, is that even though single black women are less likely to abort than other groups of single women, black women still have more abortions because they are far more likely than their white counterparts to be single. “Some portion of the racial disparities in abortion are yet another cost of the marriage decline” among blacks.