Safer sex? The effect of AIDS risk on birth rates.

Behavioral adjustments to mitigate increasing risk of STIs can increase or decrease the likelihood of pregnancy. This paper measures the effects of the arrival and spread of AIDS across U.S. cities in the 1980s and 1990s on births and abortions. I show that the AIDS epidemic increased the birth rate by 0.55 percent and the abortion rate by 1.77 percent. I find support for two underlying mechanisms to explain the increase in pregnancies. Some women opted into monogamous partnerships in response to the AIDS epidemic, with a corresponding increase in the marriage rate and improvement in infant health. Others switched from prescription contraceptive methods to condoms. These behavioral changes lowered the incidence of other sexually transmitted infections, but increased both planned and unplanned pregnancies.