Recent CDC data on youth risk behavior affirms a troubling trend: While rates of teenage pregnancy are falling—a relief to everyone except maybe the producers of MTV’s 16 and Pregnant—teens that are having sex are increasingly doing so without contraceptives.

First the good news: According to the annual National Youth Risk Behavior Survey, in 2017 “there was another decline in the percentage of high school students who report that they have ever had sex and those who have had four or more sexual partners—the lowest levels since CDC began conducting the survey in 1991.” Since 2007, the number of teens who reported ever having sex has declined 8 percent, from 47.8 percent to 39.5 percent, suggesting that the average age at which people are becoming sexually active is rising. The number of teens who have had sex with four or more sexual partners has seen an even more dramatic decrease: from 14.9 percent in 2007 to 9.7 percent in 2017.

At the same time, teenagers who reported using a condom the latest time they had sex also declined: from 61.5 percent in 2007 to 53.8 percent in 2017. The most recent data tracks with a Centers for Disease Control and Prevention report from 2017 that revealed that, after condoms, the most commonly used form of birth control for teenage girls was the pull-out method (60 percent use for those surveyed).

That’s concerning for two reasons. The first is that, according to data from the Guttmacher Institute reported by CBS, “perfect use” of the pull-out method will still result in pregnancy within a year for about 4 percent of couples. Perfect use is pretty rare, and a more realistic estimate of “typical use” would result in about 18 percent of couples becoming pregnant within a year. “Experts say the number for inexperienced teens is likely much higher,” writes CBS health editor Ashley Welch. The second is that pulling out does nothing to protect against STIs. The fact that more than half of sexually active teens report not using a condom is particularly troubling when taken into consideration with the fact that CDC data estimates that “half of the 20 million new STDs reported each year were among young people, between the ages of 15 to 24.”

And the problem is likely to get worse now that President Donald Trump has wholeheartedly supported abstinence-only sex education. Funding for abstinence-only sex education decreased under Obama, and while the decline of the teenage birth rate started long before Obama entered office, his full-throated support of comprehensive, scientifically sound sex education was no doubt influential in helping that number drop steadily lower. But according to Intercept investigative reporter Jordan Smith, “the Trump administration is trying to reverse course.”

Along with the return to Bush-era funding levels to push the ab[stinence]-only message, Trump has appointed anti-abortion, anti-birth control, and pro-ab-only advocates to positions within the Department of Health and Human Services and has yanked funding for a successful evidence-based teen pregnancy prevention strategy.

Roe v. Wade’s now-uncertain future only throws another wrench into the works. It’s not improbable that in our lifetime we’ll not only see a reversal of the downward trend of the teen pregnancy rate but also continue seeing an increase in risky sexual behavior among teens. There’s hope in the fact that teens seem to be putting off sex until later, but since researchers aren’t entirely sure what’s causing that change, it might also be subject to reversal with the reintroduction of abstinence-only sex education. What this all means is that parents are even more responsible for providing comprehensive and honest information around sex to their children. Have “the talk” early—and have it often.