The Effect of Abortion Legalization on the Incidence of Sexually Transmitted Diseases

The risk of an unwanted pregnancy represents one of the major costs of sexual activity. When abortion was legalized in a number of states during the late 1960s and early 1970s (and nationally with the 1973 Supreme Court case of Roe v. Wade), this cost was reduced as women gained the option of terminating an unwanted pregnancy. We predict that abortion legalization led to an increase in sexual activity, accompanied by an increase in sexually transmitted diseases. Using CDC data on the incidence of gonorrhea and syphilis by state, we test the hypothesis that judicial and legislative decisions to legalize abortion lead to an increase in sexually transmitted diseases. We find that gonorrhea and syphilis incidences are significantly and positively correlated with abortion legalization. According to our estimates, abortion legalization might account for as much as one third of the average disease incidence.