From 2007 to 2013, births to teens age 15 to 19 dropped by 36 percent; pregnancies fell by 25 percent from 2007 to 2011, according to federal data
But that wasn't because teens were shunning sex. The amount of sex being had by teenagers during that time period was largely unchanged, says the study
(PDF), which was published online in the Journal of Adolescent Health. And it wasn't because they were having more abortions. Abortion has been declining
among all age groups, and particularly among teenagers.
Rather, the researchers from the Guttmacher Institute and Columbia University found that "improvement in contraceptive use" accounted for the entire reduced risk of pregnancy over the five-year period.
"By definition, if teens are having the same amount of sex but getting pregnant less often, it's because of contraception," said Laura Lindberg, the study's lead author and a Guttmacher researcher.
No single contraceptive method stood out as singularly effective, said the researchers. Instead, they found that teens were using contraceptives more often, combining methods more often, and using more effective methods, such as the birth control pill, IUDs and implants.
Also, the use of any contraceptive at all makes a big difference, said Lindberg. "If a teen uses no method they have an 85 percent chance of getting pregnant [within a year]. Using anything is way more effective than that 85 percent risk."
The downturn in teen births actually dates back to the early 1990s, the authors say, with the rate dropping by 57 percent between 1991 and 2013. The increase in contraceptive use dates to the mid-1990s, with the use of any contraceptive at the most recent sexual encounter rising from 66 to 86 percent from 1995 to 2012.
Valerie Huber, who advocates for programs that urge teens to wait to have sex rather than provide information about contraception, says the study is biased toward birth control.
"As public health experts and policymakers, we must normalize sexual delay more than we normalize teen sex, even with contraception," said a statement from Huber, president and CEO of Ascend
, a group that promotes abstinence education. "We believe youth deserve the best opportunity for a healthy future."
More recent policy changes could help drop the teen pregnancy rate even more. One is the Affordable Care Act requirement
that boosted insurance coverage for contraception, starting in 2012. The other is the 2014 recommendation
from the American Academy of Pediatrics that sexually active teenagers be offered "long-acting reversible contraception" methods such as implants and intrauterine devices, which are highly effective and do not require any additional action, such as remembering to take a daily pill.
But Lindberg noted that just as for older women, teens should be offered a full choice of contraceptives. "In the end, the best method for anyone is one that they are willing and able to use."