AUSTIN, Texas (AP) -- More than four-fifths of school districts offer no sex education or only teach abstinence in Texas, which has one of the country's highest teen birth rates, according to a study released Tuesday.

The study commissioned by Texas Freedom Network, a left-leaning education watchdog group, found that 25 percent of roughly 1,000 school districts statewide didn't offer any sex education during the 2015-2016 school year and about 58 percent only taught students to abstain from sex.

The remaining 17 percent, including eight of the 10 largest school districts in America's second most-populous state, stress abstinence, which they are required to do under a 1995 Texas law. But they also teach students about other sexual topics, including birth control.

The 17-percent figure is actually a marked increase from a 2009 study, which found that 96 percent of Texas school districts taught abstinence only.

The number of districts that offer no sex education rose even more dramatically, from 2 percent in the study eight years ago to a quarter of them today. A major factor in districts dropping their sex education curriculums was a 2009 decision by the Republican-controlled Texas Legislature to scrap passing a health course as a high school graduation requirement.

Of the districts that still teach sex education, 31 percent of the ones in urban areas offer instruction on more than just abstinence, while only about 5 percent of rural districts do.

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