(Reuters Health) - U.S. government spending on abstinence-only education doesn’t appear to reduce teen pregnancies and in some areas is having the opposite effect, a recent study suggests.

Across the country, government-funded abstinence-until-marriage education did not predict a reduction in teen births - and in conservative states, it was associated with higher adolescent birth rates, the study found.

“It was actually opposite of what we had hypothesized,” said Ashley Fox, of the Rockefeller College of Public Affairs and Policy at the University of Albany, New York, in a phone interview.

Fox and colleagues analyzed data on more than $2 billion in federal grants for abstinence-only education and sexuality education (including pregnancy prevention) between 1998 and 2016, along with adolescent birth rates.

For the country as a whole, money spent on abstinence-only programs had no effect on adolescent birth rates, the researchers found. Similarly, there was no overall effect of sexuality education on adolescent births.

But when researchers looked at individual states, they found the effects varied by state ideology, with both kinds of programs having significant impacts in conservative states.

For every $1.00 per pupil increase in funding for abstinence-only education, the teen birthrate rose by 0.30 per 1,000 in conservative states compared with moderate states, the researchers found.

In the same conservative states, however, funding of pregnancy-prevention education was linked with decreases in adolescent births. For every $1.00 per pupil increase in funding for pregnancy-prevention education, the teen birthrate went down by 2.42 per 1000 in conservative states compared with moderate states.

Supporters of abstinence education believe schools shouldn’t teach about contraception and safe sex because such information legitimizes and inadvertently endorses out-of-wedlock sexual activity, the researchers explain in the American Journal of Public Health. Supporters of comprehensive sex education believe students should be taught age-appropriate, medically accurate information on topics related to sexuality.

Conservative states have consistently had higher adolescent pregnancy and birth rates, the researchers note. Fox suggests this could be because teens in conservative states who want to practice safe sex have less support, both culturally and in terms of accessories like contraceptives.

Liberal and moderate states, however, have higher abortion rates than do conservative states, resulting in lower birth rates, the authors point out.

The study can’t prove that abstinence education or sex education actually causes teen birth rates to change. Furthermore, while the authors tried to account for factors that might have influenced the results, they lacked data on important variables, including abortion rates.

In 2017, teen pregnancies in the U.S. were at a record low, at 18.8 per 1,000 among young women ages 15 to 19, according to the U.S. Centers for Disease Control and Prevention. But that’s still substantially higher than in other western industrialized nations, the agency noted.

U.S. funding for abstinence-only education declined under President Barack Obama, but President Donald Trump’s proposed 2018 budget included $277 million in new funding for abstinence-only education.

Dr. Mara Horwitz of the Harvard Pilgrim Health Care Institute in Boston told Reuters Health the study’s implications are significant because sex education funding decisions should be based on evidence of what actually works.

“This information could help policy-makers distribute limited funds for maximum impact,” Horwitz, who was not involved in the study, said by email, adding that education programs that give teens the knowledge, tools, and self-efficacy to practice “safe sex” and become comfortable with their sexuality - especially in more ideologically conservative states - could have a positive impact on teen pregnancy rates.

SOURCE: bit.ly/2Us4lgF American Journal of Public Health, online February 6, 2019.