Higher rates of illegitimacy because of legal abortion?

That's what John Lott Jr. opines in the Wall Street Journal.

From the beginning of the abortion debate, those favoring abortion have pointed to the social costs of "unwanted" children who simply won't get the attention of "wanted" ones. But there is a trade-off that has long been neglected. Abortion may eliminate "unwanted" children, but it increases out-of-wedlock births and single parenthood.

This reminds me of something Ramesh Ponnuru wrote in his book Party of Death (pages 69, 71):

Freakonomics got this much right: The legalization of abortion caused the number of conceptions to go up 30 percent, while causing the number of birth to go down by only 6 percent.

Many of the unborn children who have been aborted since Roe, in other words, would never have been conceived in the first place without it.....

(Legalized) Abortion may not lead to fewer unwanted children; it may lead to the birth of more children who aren't wanted by their fathers. While this result may sound counterintuitive - and some research supports the opposite view - it is worth noting that abortion and illegitimacy rate rose in tandem during the 1970s and have fallen in tandem since the 1990s.