Between 1982 and 2017, Congress spent over $2 billion on programs which teach teens that the best way to address their desire to have sex is to wait until they get married, according to a new study published in the September issue of the Journal of Adolescent Health.

Called abstinence only until marriage (AOUM), these programs accurately explain that the best way to avoid pregnancy and sexually transmitted diseases is to not have sex. They also fail teens spectacularly by not divulging critical information about the mechanics, emotions, responsibilities and consent issues involved in having healthy sexual relationships. Promoting these programs could constitute a violation of medical ethics, says Laura Lindberg, a coauthor of the report and a research scientist at the Guttmacher Institute, in an interview with NPR.

“We tell people not to drink and drive,” she added. “We don’t teach them not to drive. … We would never withhold information about seat belts because they wouldn’t know how to protect themselves.”

President Trump recently cut more than $213 million in federal funds for teen pregnancy prevention programs at more than 80 organizations. According to the new study, his 2016 budget awarded $85 million to AOUM programs (compared to $176 million for more comprehensive sexuality education through the Teen Pregnancy Prevention Program and Personal Responsibility Education Program).

From 1995 to 2011–2013, the share of US adolescents who received instruction on abstinence but no instruction about birth control methods, increased from 8% to 28% of females and from 9% to 35% of males, according to the report.

Arguments in favor of abstinence-only approaches tend to be religious or cultural. Advocates of abstinence until marriage argue that explaining how to have sex healthily amounts to tacit encouragement. “We are surrendering to the idea that teenagers will be sexually active,” Penny Nance, CEO of Concerned Women for America told NPR.

But the report highlights a few shortcomings in the AOUM approach. Scientific evidence shows the approach doesn’t actually delay teens having sex, or engaging in risky sexual behaviors. The programs also sometimes provide misleading or inaccurate information about contraceptive effectiveness and sex itself.

There are other important reasons to teach kids about sex and the issues around it, like educating them about consent, LBGT rights, and sexual violence. One in five women reported being sexually assaulted during college, a 2015 national report from the National Sexual Violence Resource Center found.

According to a recent report from Harvard’s Making Caring Common project, more than half of 18-25-year-olds surveyed never had a conversation about “being sure” a partner wants to have sex. “For adults to hand over responsibility for educating young people about romantic love—and sex—to popular culture is a dumbfounding abdication of responsibility,” the authors wrote.

Abstinence-only might have been a successful strategy in for women born in the 1940s, since the interval between first having intercourse and getting married was one to one-and-a-half years.

But teens are having sex sooner and marrying later, making a national policy of “just don’t do it” fanciful. The median age at which women first have sex is now about 17.8 years (where it has been for awhile), while the median age for first marriage is 26.5 years. That’s an almost nine-year gap. For men, the gap is wider, at 11.7 years (sex at 18.1 years and first marriage at 29.8 years).