The United States has not made any significant advances in sexual education in the last five years, according to a new study. Researchers found that when it comes to middle and high schools teaching students about preventing unwanted pregnancy and protecting themselves against HIV and other STDs, the country is not moving forward -- and in some areas, it is actually regressing.

Forty-five states took part in a survey between 2008 and 2010 that assessed what percentage of schools taught specific sex-ed topics. Although the material differed between middle and high schools, basic information such as how STDs are transmitted and how to prevent pregnancy were common in both.

Researchers analyzed the data and found that in 2010, there were no states that had an increase since 2008 in the number of schools offering sex education -- and 11 states had a lower percentage of schools offering programs.

Little progress has been made in the proportion of middle and high schools that offer education on the prevention of HIV, many STDs, and pregnancy, Laura Kann, study coauthor and a CDC researcher, told WebMD. We are heading in the wrong direction.

What's more alarming, according to the study, is the disparity between what is taught in different states. In 2010, correct condom usage was taught in 26.8 percent of public high schools in Utah compared to 96.6 percent of Delaware high schools. With nearly half of all high school students sexually active, researchers said it's important to make sex-ed a part of education again.

From the early 1990s until now, we were seeing a decline in the number of high school students who were sexually active, Kann told WebMD. The decline has leveled off and we are concerned that the rate could go back up.

There are only two kinds of sexual education taught in the United States, according to the Kaiser Family Foundation. The first, abstinence plus, teaches students that refraining from sex is a good choice, but also teaches about contraception. The second, abstinence-only, teaches students that sex should wait until marriage and does not provide information about contraception. A Kaiser study found that 34 percent of high-school principals said their school teaches abstinence-only education.

In an article accompanying the study, researchers said that educating kids before they become sexually active is especially important and could help curb the infection rate of HIV and STDs.

HIV prevention can also address misperceptions about how HIV is transmitted, researchers wrote.  Twenty percent of persons aged 18-29 believe incorrectly that a person can become infected with HIV by sharing a drinking glass, or are unsure of whether this statement is true or false.

Many parents might object to sexual education being taught in schools, but schools are in the perfect position to do so, the researchers said.

Families, the media, and community organizations, including faith-based organizations, can play a role in providing HIV, other STD, and pregnancy prevention education, they said. However, schools are in a unique position ... because almost all school-aged youths in the United States attend school.

The journal Morbidity and Mortality Weekly Report published the study on April 6.