Formal instruction about birth control and other aspects of sexual health in the U.S. is on the decline, according to an analysis of survey data from 2006 to 2013.

"The declines in formal sex education we observed since 2006 are distressing, but unfortunately are part of a longer term retreat from sex education, especially instruction about birth control methods," said lead study author Laura Duberstein Lindberg of The Guttmacher Institute in New York.

"For example, in 1995 more than four out of five teens were taught about birth control-in the most recent data this is only about half," she said.

The researchers used interviews taken from nationwide household surveys administered continuously between 2006 and 2010 and between 2011 and 2013, focusing on respondents aged 15 to 19 years. The analysis included responses from about 2,000 teen boys and 1,000 teen girls in each wave of surveys.

The surveys included questions about whether the youth had ever received formal sex education at school, church, a community center or elsewhere before age 18. Examples of sex education topics used in the surveys included how to say no to sex, methods of birth control, sexually transmitted diseases and how to prevent HIV and AIDS. The second wave of surveys also asked about learning where to get birth control and how to use a condom.

In addition, the teens reported whether they had ever discussed these topics informally with a parent or guardian.

In the 2006 to 2010 surveys, 70 percent of girls and 61 percent of boys said they had received formal instruction about birth control, which dropped to 60 percent and 55 percent, respectively, in the 2011 to 2013 surveys.

Girls also reported less formal education on STDs, HIV and AIDS prevention, and saying no to sex over time. Both girls and boys reported more formal education in saying no to sex without instruction about birth control in the second survey wave, the researchers report in the Journal of Adolescent Health.

Most of the decline in reported formal sex education happened in rural areas, the study team notes.

Informal sex ed talks with parents did not appear to change over time.

About one in five girls and more than a third of boys said they had received no instruction on birth control from formal sources or from a parent.

"The ongoing changes in the public education system likely explain some part of it," said Brian Goesling of Mathematica Policy Research in Princeton, New Jersey, who was not part of the study. "Schools are placing more emphasis on academic standards and student achievement. They may have less time for formal sex education."

What happens in a particular school depends mostly on state and local educational policy, he told Reuters Health by email.

"Sex education has long been contentious and political in the U.S.," Lindberg told Reuters Health by email. "Abstinence-only until marriage programs took over sex education in the late 1990s, and instruction about birth control has declined ever since."

At the same time, concern about HIV declined, reducing prioritization of sex education, she said.

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"Too many teens are falling through the gaps, without instruction from parents or formal settings," she said. "Too few teens receive sex education before they first have sex."

While teen pregnancy has also been on the decline, that drop could have been greater if comprehensive sex education were more widespread, Lindberg said.

"Parents need to talk with their children about sex, about sexuality and about normal healthy development," not as a single conversation, but as part of the ongoing job of being a parent, she said. "Parents can also be important advocates for other sources of sex education, working with their child's school and pediatrician to ensure that their child has access to the education that they need."

SOURCE: http://bit.ly/1T6IGUS Journal of Adolescent Health, online March 29, 2016.