More Than Half of Teens Are Having Sex and Most Use Birth Control

Just over half of American teenagers are sexually active, and most report using some form of contraception, according to new research.

The study from the National Center for Health Statistics found that 55% of teens said they were having sex by age 18, and 80% of those teens used some form of protection during their first time. The findings come from surveys with 4,134 male and female teens ages 15 to 19 from 2011 through 2015.

Overall, fewer teens are having sex now than in the past. 42% of teen girls and 44% of teen boys reported having sex at least once—down about 9% for girls and 16% for boys from when the government group began tracking such numbers in 1988. The most common reasons teens gave for not having sex was that it was against their religion or morals, that they hadn’t found the right person yet or that they didn’t want to get pregnant (or get someone pregnant).

Most of the teens—74% of girls and 51% of boys—had sex for the first time with someone they were in a relationship with. Only 2% of girls and 7% of boys said they had sex for the first time with someone they had just met.

Most teens also reported using contraception, especially girls. 99% of girls reported using some contraceptive method in 2011-2015.

MORE: See How Every Form of Birth Control Actually Works

However, teens weren’t always using the most effective kinds. Most widely used was the condom, which has an 18% failure rate, followed by the withdrawal method (with a 22% failure rate) and the pill (which has a typical-use failure rate of 9%). The study authors note that long-acting methods like the IUD and implant were redesigned in the early 2000s and hadn’t been widely adopted enough to get accurate estimates. Past research suggests that teens may not use these methods because they don’t know about them or think they are too young to use them.