Teen pregnancy prevention programs don’t always work as intended, but researchers say sex education and access to contraception make a difference.

Experts and parents have long been in agreement: No one wants teenagers to have unwanted pregnancies.

But there’s a lot of debate about the best way to prevent teen pregnancy.

Now, researchers in Australia say they believe there is one approach that can be ruled out.

According to their study published in The Lancet, school programs that use baby simulators may actually increase the risk of pregnancy for teen girls.

Baby simulators are electronic dolls designed to mimic the needs of a real baby.

The dolls cry to be fed, burped, rocked, and changed. They also have an internal monitoring system that tracks crying time, number of diaper changes, and any mistreatment.

In the United States, the program is often called “Baby Think It Over.”

Theoretically, caring for the dolls is supposed to be so difficult that teens are motivated to avoid an unplanned pregnancy — but it may not actually work that way.

Read more: Is long-term birth control the best way to reduce pregnancies? »

The Australian study followed nearly 3,000 teen girls ages 13 to 15 up until the age of 20.

Of those, 1,267 girls took part in an education program that used the baby simulators, while 1,567 girls were in a control group that didn’t use the dolls.

By checking medical records, the researchers tracked how many teens in each group got pregnant.

They found that teens who cared for baby simulators were 7 percent more likely to become pregnant compared with the control group.

That means that not only did the baby simulator program not work, but it seemed to actually cause an increase in the teen pregnancy rate, according to Sally Brinkman, Ph.D., a scientist with Telethon Kids Institute, and the study’s lead author.

The study has been criticized because girls in the control group were slightly more affluent than those who used the baby simulators, but Brinkman said the final results accounted for those differences.

In general, she said the two groups were similar and any economic differences would only change the magnitude of the results — not the overall finding.

“From a scientific point of view, there’s no way that you could turn the results that are currently negative into a positive,” Brinkman told Healthline.

Realityworks, the company that manufacturers the dolls, also criticized the study for not following the curriculum it developed to go with the baby simulators.

But Australia’s national sex education curriculum that all of the teens studied covers the same material, Brinkman said.

“We don’t think it’s a matter of tweaking the program in any way. It doesn’t work,” she said.

The researchers recommended that the Australian education department stop using the dolls.

In the United States, Realityworks reports that its baby simulators are used in two-thirds of American school districts.

Ending programs that use the dolls may be an uphill battle, since teens and teachers enjoy them.

Brinkman said some students loved the program so much it was hard to get them to return the baby simulators.

“In the education system, there are a lot of programs that are delivered because students like it and they engage well. That doesn’t necessarily mean those programs are good,” Brinkman added.

Read more: Mental health effects of teen pregnancy »

Since the 1960s, teen birth rates have fallen dramatically worldwide, including in the United States, according to data from the United Nations Population Division.

But the United States still has one of the highest teen birth rates among developed countries.

The U.S. rate is 24 births per 1,000 adolescent girls, ages 15 to 19.

That’s more than double the rate in Canada and more than quadruple the rates in Denmark and Japan.

Teen pregnancy carries serious personal and financial costs.

The federal Office of Adolescent Health (OAH) reports that teen moms are less likely to finish high school and more likely to be poor as adults, In addition, their children tend to have more health problems and behavioral issues compared with kids whose parents are older.

Taxpayers also pay a hefty price. The OAH estimates the cost of teen pregnancy is in the billions of dollars due to things like social assistance payments, public health services, and foster care.

That’s why research into the best ways to curb the teen pregnancy rate is so important — and scientists are starting to find answers.

According to a large research review published earlier this year, the most effective programs to prevent teen pregnancies include two key components: education and access to contraception.

Conducted by Cochrane, a network of independent researchers, the review included more than 50 studies with a total of more than 100,000 teen participants.

The review found that programs that only provided education, or only promoted access to birth control, weren’t effective at reducing teen pregnancy.

Chioma Oringanje, lead author of the review, told Healthline that the most effective programs tend to include:

  • education about sexual practices and consequences
  • information on how to get contraception
  • skill building to empower teens to make good decisions

“The best interventions to prevent teenage pregnancy use a multidimensional approach,” Oringanje added.

Read more: CDC continues aggressive push for HPV vaccination for preteens »

For young people in Colorado, that type of multidimensional approach may have helped prevent a lot of unplanned pregnancies.

From 2009 to 2014, the teen birth rate in Colorado dropped by 48 percent.

Although teen birth rates fell nationwide during those years, Colorado had the biggest decrease of any state in the country.

Government officials credit the success to the Colorado Family Planning Initiative, a collaboration of state agencies, school boards, and nonprofit organizations.

The initiative led to big changes, including more comprehensive sex education classes in Colorado schools and improved access to contraception for teens.

Such changes are often controversial, but that wasn’t the case in Colorado, according to Lorena Garcia, Director of Development and Strategic Communications for Colorado Youth Matter, one of the nonprofit organizations behind the initiative.

Garcia said there was widespread public support for providing teens with better sex education and access to birth control.

She also noted that promoting long-acting reversible contraceptives, such as IUDs and birth control implants, may have been a big part of why Colorado’s teen birth rate dropped.

The initiative provided 36,000 of those birth control options for free at family planning health centers.

Colorado Youth Matter continues to help schools improve sex education curricula and to build links between schools and clinics, where teens can access contraceptives or get confidential advice.

Last year, the organization received a federal grant to focus on reducing teen birth rates in certain Colorado counties that still lag behind the rest of the state.

Garcia is optimistic their approach will continue to work.

“A lot of research shows that when you provide young people with the accurate, unbiased information, they are able to make responsible decisions for their own situation,” Garcia told Healthline.