Sex education, which teaches teens about condom use, among other things, doesn't seem to reduce teen birthrates in conservative states.

Sex education is failing to reduce adolescent birthrates in conservative states, according to a new study.

Perhaps paradoxically, states with a majority conservative population and higher degree of religiosity tend to have higher teen birthrates. The findings suggest that the social structure of the state, such as the degree of conservatism, can undermine the effect of the sex curricula.

The researchers, from Washington University in St. Louis (WUSL), do not recommend abstinence-based education, but rather crafting sex education curricula that take into account the influences of a state's sociopolitical composition. The study appears today (Feb. 6) in the Archives of Pediatrics & Adolescent Medicine.

High rates but falling

The U.S. adolescent birthrate is by far the highest among industrialized nations. The birthrate among girls ages 15 to 19 was 39.1 per 1,000 teens in this age group in 2009, the most recent year for which statistics are available. The rate in Western Europe ranges from about 24 per 1,000 teens in the U.K. (slightly lower than the U.S. white non-Hispanic rate) to four in the Netherlands.

Broken down by race, the U.S. rate ranges from 70.1 among Hispanic Americans to 14.6 among Asian Americans, according to the Centers for Disease Control and Prevention (CDC).

The rate is falling, however, and is at its lowest point since recordkeeping began 70 years ago. Health experts cannot fully explain the cause for the decline after a recent peak in the 1980s, nor do they know the reason for disparity from state to state. Thus, there is an ongoing debate over the efficacy of comprehensive sexuality-based programs, which teach about both abstinence and condom use to reduce the risk of pregnancy and sexually transmitted diseases, compared with abstinence-based programs, which exclude information about birth control and safe sex.

Sexually active in red states

Researchers led by Patricia Cavazos-Rehg of WUSL narrowed their analysis to birthrates among girls ages 15 to 17 in 24 U.S. states during years of steady decline from 1997 to 2005. (The national birthrates climbed slightly in 2006 and 2007 before declining again in 2008 and 2009.) They found what many researchers have stated previously — that an increase in comprehensive sex education in school is associated with lower adolescent birthrates. [10 Surprising Sex Statistics]

The association disappears, however, when the researchers controlled for state characteristics, such as religiosity and abortion policies. The apparent irony is that states with higher religiosity rankings and greater political conservatism had higher adolescent birthrates.

That much was not a total surprise. Researchers at Drexel University reported a similar finding in 2009 in the journal Reproductive Health. The latest findings provide the added twist that a state's level of conservatism might compromise the value or quality of sex education.

The WUSL researchers postulate that girls living in conservative states or counties either get a watered-down version of the sex education curriculum, disregard the lesson, or are less willing or able to have an abortion, all leading to higher statewide teen birthrates.

Arkansas vs. New Hampshire

"State adolescent births vary widely, and these disparities across states should be acknowledged as a major public health concern," Cavazos-Rehg told LiveScience. She noted the difference in birthrates among girls ages 15 to 17 in Arkansas and New Hampshire. Arkansas, with high conservatism, had the highest birthrate in this study, 34.8 per 1,000 girls in this age range. New Hampshire, with high liberalism, had the lowest birthrate, 9.7. [Teen Pregnancy: A 'Winnable' Public Health Battle?]

Yet the analysis failed to consider pregnancy rates, which Cavazos-Rehg said are more difficult to obtain than birthrates. Could it be that, despite sex education, girls in both conservative and liberal states are getting pregnant at about the same rate, and that the girls in Arkansas are carrying their babies to term, perhaps as a result of higher religiosity, a lack of access to abortion services, or both?

The analysis also assumed that statewide data faithfully represented all schools within the state. But states are large geographic entities with many different school districts and schools, which individually make choices about what to offer in terms of sex education. Policies are made primarily at the local and individual school level.

"The study shows the difficulty of mounting an intervention at the state level that would be sufficient to shift teenage birthrates," said Freya Sonenstein, director for the Center for Adolescent Health Promotion and Disease Prevention at Johns Hopkins Bloomberg School of Public Health. "But at the local and school levels, there is plenty of other evidence that implementing particular curriculums can produce improvements in students' risk-taking behaviors."

Cavazos-Rehg said she hopes to conduct a follow-up study with data on pregnancy and sexual behavior. Yet for now, she added, "though it still remains unclear as to what 'truly effective' sex education is, what we now know is that any future evaluations of sex education must consider the effects of sociopolitical characteristics in comprehensive analyses."

Christopher Wanjek is the author of the books "Bad Medicine" and "Food At Work." His column, Bad Medicine, appears regularly on LiveScience.