Objectives. To examine the relationship between adolescent pregnancy–prevention and sexuality and abstinence-only education funding and adolescent birthrates over time. Also, to determine whether state ideology plays a moderating role on adolescent reproductive health, that is, whether the funding has its intended effect at reducing the number of adolescent births in conservative but not in liberal states.

Methods. We modeled time-series data on federal abstinence-only and adolescent pregnancy–prevention and sexuality education block grants to US states and rates of adolescent births (1998–2016) and adjusted for state-level confounders using 2-way fixed-effects models.

Results. Federal abstinence-only funding had no effect on adolescent birthrates overall but displayed a perverse effect, increasing adolescent birthrates in conservative states. Adolescent pregnancy–prevention and sexuality education funding eclipsed this effect, reducing adolescent birthrates in those states.

Conclusions. The millions of dollars spent on abstinence-only education has had no effect on adolescent birthrates, although conservative states, which experience the greatest burden of adolescent births, are the most responsive to changes in sexuality education–funding streams.