It’s known as withdrawal, the “pull out method,” and, in scientific communities, coitus interruptus. But regardless of what you call it, the act is the same — removing a penis from a vagina before ejaculation, in hopes that it’ll reduce the chance of pregnancy. While scientists still debate its usefulness as a contraceptive method, a new nationwide study makes one thing clear: It’s an increasingly popular method among American men.

In a data brief released Thursday, the National Center for Health Statistics reveals that withdrawal became increasingly popular from 2002 to 2015. Between 2011 and 2015, approximately 18.8 percent of men used withdrawal as their primary form of contraception. In 2002, that number was 9.8 percent, and it was 14.5 percent between 2006 and 2010.

This report, based on interview data from 3,707 unmarried men between the ages of 15 and 44 who had sex within three months of the interview, broke the male population down by both relationship status and age. The analysis showed that withdrawal was most frequently used among never-married men, followed by “formerly married” men.

Breaking the data down by age show that withdrawal is used most by teens — males between 15 and 19 — with 26.2 percent of that group using it. Next came men aged 20 to 24, where 21.6 percent of the population had used it.

Percentage using any and selected contraceptive methods at last sexual intercourse in the last three months.

Despite its growing popularity, withdrawal remains very difficult to do correctly, and it doesn’t protect anyone from sexually transmitted infections, regardless of whether semen is spilled.

“The failure of withdrawal to provide adequate protection against STIs is one important reason clinicians may be reluctant to promote it, and reliance on withdrawal alone is inappropriate for certain high-risk populations,” reads a 2009 report supported by the Guttmacher Institute.

Withdrawal is less effective than condoms at preventing pregnancy (but surprisingly, not by much). Numerous studies reiterate that with “perfect use” of the withdrawal method, four percent of couples will become pregnant. That number rises to 18 percent with “typical use.”

Meanwhile, when couples use condoms perfectly, there’s a two percent chance of pregnancy, while “typical” use can result in a 17 percent chance.

A contraception guide made by the CDC.

When it comes to preventing pregnancy, success is based on the ability to pull out perfectly, which is difficult to do for numerous reasons. Part of the gamble stems from the fluid released before ejaculation. In 2011, scientists reported in the journal Human Fertility that the pre-ejaculate of some men can indeed include live sperm.

“[Condoms] should continue to be used from the first moment of genital contact,” the researchers write, noting that some men just have less sperm in their pre-ejaculate, making them able to “practice coitus interruptus more successfully than others.”

They note that it was hard to measure the amount of sperm in their participants’ pre-ejaculate because many of the men finished earlier than they expected.

“If our aim was to determine whether delaying either condom use or withdrawal (if using coitus interruptus) to immediately prior to ejaculation posed a threat for unintended pregnancy,” they write, “then the fact that some men might be able to judge this moment is enough to answer the question.”

Percentage using withdrawal at last sexual intercourse among unmarried men aged 15-44.

If people do choose to use the withdrawal method, researchers recommend that they pair it with another contraceptive method, like birth control or condoms. This reduces both the chance of pregnancy and the risk of sexually transmitted infections.

“Withdrawal can provide ‘extra insurance’ against pregnancy for all couples, even those using hormonal methods,” Rachel Jones of the Guttmacher Institute said in a statement in conjunction with her study. “And withdrawal is far more effective at preventing pregnancy than use of no method at all.”

The good news is that American men are on board with contraception: According to the NCHS data brief, nearly 82 percent of unmarried men report using some form of contraception when they have sex.