The Wall Street Journal and the American Spectator have sunk to an embarassing low with the publication of an Levine, Trainor and Zimmerman (1996), find just this. LTZ estimate that restrictions on Medicaid funding of abortions reduced the number of abortions but the number of pregnancies fell even further so the number of births actually went down not up.
Putting things the other way, compensating behavior means that abortion liberalization will reduce the number of births by less than the number of abortions. Five states legalized abortion in 1970, prior to Roe v. Wade (Alaska, California, Hawaii, New York, and Washington). Levine, Staiger, Kane and Zimmerman (1999) estimate that births in these states fell by 5% more than in states that had not legalized abortion. Applying this number to today’s rates they estimate “a complete recriminalization of abortion would result in 320,000 additional births per year.” Since there are about 1.3 million abortions a year, only about a quarter of all abortions represent a net reduction in births.
The reduction in births, even though considerably smaller than than the number of abortions, is not distributed randomly across the population so abortion policy can have an impact on things like crime and teenage pregnancy but the number of Democrats and Republicans has got to be one of the least interesting consequences.
Hat tip to MemeFirst for alerting me to the article.