Let’s hear it for the teens! With a little help from a few grownups, the teenagers of America seem to be figuring out how to keep their futures on track—or at least keep them from going off the rails by having a baby when they should be doing homework.

The National Center for Health Statistics just released new data showing that the number of births to girls 15-19 years old is the lowest it’s been since 1933, the year the government started tracking it. In 2013 alone, both the number and the rate of teen births dropped by an astounding 10 percent. This means that since the peak year for teen childbearing in the 1970s, the rate of teen pregnancy has plummeted by 57 percent. The best news is for the high school-age kids; among girls ages 15-17, there’s been a 68 percent drop in the pregnancy rate.

When a major social problem starts melting away, you’ve got to ask what’s going on—and how we can keep the momentum going.

One side effect of the Great Recession that began in 2007 was a drop in the overall birth rate, but that doesn’t come close to explaining these numbers. Our friends at the National Campaign to Prevent Teen and Unplanned Pregnancy have sliced and diced the data, looked at the research, and come up with a handful of reasons for the dramatic improvement:

Better birth control. While still nowhere near as popular among young people as the pill, teens are increasingly choosing long-acting contraceptive methods like IUDs and implants. No muss, no fuss, no babies.

Fewer teen moms beget fewer teen moms. With the teen birth rate declining steadily since the 1990s, fewer of today’s teens have mothers who got pregnant at a young age. This is what a virtuous cycle looks like.

Medicaid pays. For 18- and 19-year-old women, Medicaid has covered family planning services in 26 states since the 1990s. In the U.S., as around the world, making family planning affordable to all pays off.

Media messagesTeen Mom and 16 and Pregnant have shown their huge audiences how hard it is to have a baby when you’re young. Combined with factual, no-nonsense information about sex and contraception, most of today’s teens are no longer in the dark.

Teenage boys. You wouldn’t think teenage boys would be on the list of explanations for a drop in teen pregnancy, but boys and young men have been having less sex and using more condoms. Prevention of HIV/AIDS is having broad benefits.

If these are the ingredients that go into preventing teen pregnancies, then we know what to do. In particular, we need to make sure that teens—both boys and girls—have the information they need to make choices about whether to have sex and how to prevent pregnancy and sexually transmitted diseases. And we need to ensure that reproductive health services are affordable, convenient, and focused on the needs of young people. While the kids are busy with their homework, that’s the assignment we’re working on.