Many teens want to avoid getting pregnant. Thanks to supportive communities and innovative programs, many are succeeding. The birth rate among teens in the United States is at an all-time low. But one key federal program, whose work has driven some of this progress, is now in danger of losing half of its funding.

The program is the Teen Pregnancy Prevention (TPP) Program, which lives within the little-known Office of Adolescent Health. The Obama administration established this pregnancy prevention program in 2010 as part of its broader, unprecedented embrace of evidence-based initiatives. The Office of Adolescent Health, also established in 2010, was given a two-tiered directive: replicate proven teen pregnancy prevention programs and evaluate the promise of innovative new strategies.

Teen birth rates have been declining since the 1990s. New data reveal an even sharper drop in the five years following the inception of the TPP program, from about 34 births per 1,000 girls in 2010 to 22 per 1,000 in 2015 — a 35 percent decrease. This unprecedented decline suggests that the Office of Adolescent Health’s funding strategy for teen pregnancy prevention has been highly effective.

Yet the Trump administration recently proposed immediately slashing the budget for this highly successful program by 50 percent.

Many people assume that the drop in unintended pregnancies has been due largely to increased funding for birth control, which can make a wider variety of methods more affordable. As long as we protect programs like Medicaid expansion and the Affordable Care Act, which increase coverage for contraceptives, so the thinking goes, unintended pregnancies will continue to decline.

But decreasing the cost of various birth control methods doesn’t guarantee an increase in their use, especially if teens don’t know about all of the methods available to them. Teens turn most often to condoms and withdrawal, both of which have high failure rates in their first year of use (18 percent for condoms and 22 percent for withdrawal). Until recently, many teens had never heard of the more effective methods available to them. For example, far fewer than half of young women had heard of intrauterine devices (IUDs) or implants, both of which have failure rates of less than 1 percent. Agencies and advocates have had to do the hard work of educating young women — and their care providers — about the full range of methods and the pros and cons of each.

Teens require especially creative outreach efforts about contraception. Their communication methods are always evolving, their privacy is paramount, and the criteria they use to select birth control can be complex. Outreach to teens must be highly customized and continually evaluated and improved — precisely what the Office of Adolescent Health has made possible through its smart, effective TPP grant making.

The team I lead, the Program in Woman-Centered Contraception at the University of California, San Francisco, was fortunate to receive a five-year TPP innovation grant in 2015. In partnership with The National Campaign to Prevent Teen and Unplanned Pregnancy, we have designed an innovative intervention called SpeakOut that combines offline and online outreach to harness the power of social networks and peer influence to improve teens’ awareness of their birth control options. Like all TPP programs, SpeakOut’s design is driven by evidence — in this case, evidence about how teens prefer to learn and communicate with one another about birth control options.

In 2016, we began a rigorous evaluation of SpeakOut. If proven effective — which our pilot results suggest it is — it can be replicated and disseminated nationally. Meanwhile, 80 other TPP grantees are currently scaling up proven strategies and evaluating other new and innovative approaches for reaching adolescents across the country.

The Trump administration’s call to drastically cut funding for these programs endangers this progress. The administration has previously claimed that cuts to federal programs like TPP are meant to produce savings. While cost should never be the deciding factor when it comes to optimizing women’s reproductive health, teen pregnancies are far more expensive than the cost of helping teens who want to prevent them. The National Campaign estimated that in 2010, teen pregnancies cost the US roughly $9.4 billion — about 90 times more than the annual Teen Pregnancy Prevention Program budget of $101 million. And teens who avoid unintended pregnancy don’t just save the system money — they learn more and earn more, too.

After revealing his initial budget, Trump called on the federal government to, “Do so much more with the money we spend.” His administration will be hard-pressed to find an investment that produces a better return on investment, or brighter futures for our youth, than equipping teens with the tools they need to prevent pregnancy.

Christine Dehlendorf, MD, is the director of the Program in Woman-Centered Contraception and an associate professor in the Department of Family and Community Medicine, both at the University of California, San Francisco. The views expressed here are those of the author and do not necessarily reflect those of the University of California, San Francisco.