Teen birth rates have fallen in recent years, but the rate in the United States is higher than in other high-income countries, including the Netherlands and all Scandinavian countries.1

Researchers studied teens’ hormonal contraception use in the United States and Norway to see if these differed and whether they could explain the birth rate differences. Abortion rates between Norway and the United States are similar. About half of women in both nations experience their sexual debut before they turn 18 years of age. But teen birth rates in the United States are about six times higher than in Norway, says Katherine Ahrens, PhD, MPH, lead study author and assistant research professor at the University of Southern Maine’s Muskie School of Public Service.

The U.S. teen birth rate is 16.7 births per 1,000 teens — 73% lower than the peak in 1991. In Norway, the teen birth rate is 2.8 births per 1,000 teens.

“Why is there a difference between Norway and the U.S. in teen pregnancy rates?” Ahrens asks. “Is it because Norwegian women initiate hormonal contraception at an earlier age than U.S. women?”

This concept takes exploration of teenagers’ contraception use in a slightly different direction. Most studies look at women’s current contraception use or post-sexual debut contraception use, she notes.

Ahrens and her co-author collected data on a cohort of women, born between 1989 and 1997, in Norway and the United States to study their patterns of contraception use, particularly hormonal contraceptives.

“We wanted to see how these patterns compared between the U.S. and Norway because Norway had lower teen pregnancy rates and birth rates than the U.S.,” Ahrens explains. “We wanted to explore one aspect of contraception that we hadn’t explored before: When do teens start hormonal contraception?”

They found that Norwegian teens were more likely to have initiated contraception by age 19 years than were American teens. Among those born between 1995 and 1997, by age 19, only 26% of women in Norway had not filled a prescription for hormonal contraception. By contrast, 40.5% of U.S. women of the same age had not yet used a hormonal method.

Also, 72.8% of Norwegian respondents reported using the pill as their first hormonal method, while only 46.3% of the U.S. women reported using the pill first. American women were more likely to use the contraceptive injection, the contraceptive ring, and the intrauterine device (IUD) than were women in Norway.

The pill was the most common hormonal contraceptive used by women in both countries. “The U.S. tended to have higher uptake for those other methods, especially [injection], implants, and the IUD,” Ahrens says. “This was a descriptive study, so we don’t have a lot of explanations. The same contraceptive methods are available in both countries.”

One possible factor is the birth control pill is available at a subsidized cost in Norway. Teenagers can easily obtain the pill from providers, including nurses. Other contraceptive methods were added to Norway’s reimbursement system later, she adds.

When Ahrens and her co-author divided the women and their contraception use by year, they found that at age 15 years, U.S. teens were more likely to have started hormonal contraception than were Norwegian teens. But after age 15 years, teens in Norway were much more likely to have started to use a hormonal contraceptive.

Investigators did not explore why that difference occurred, but it is possible that 15-year-old American teens were using hormonal contraceptives for reasons other than to prevent pregnancy. “I wonder if there is more use in the U.S. of the pill or hormonal methods for non-contraceptive purposes,” Ahrens explains. “It could be teens are initiating these methods for other reasons.” For example, hormonal contraceptives can be used to prevent severe menstrual symptoms.

The next phase of research is to find out if Norwegian teens are using contraceptives more consistently than American teens. “We know certain methods are more effective at preventing pregnancy than are others,” Ahrens says. “Is Norway’s use of the pill a more effective method overall than what we’re doing in the U.S., which is a range of methods?”

REFERENCE

  1. Ahrens KA, Skjeldestad FE. Trends in initiation of hormonal contraceptive methods among teenagers born between 1989 and 1997 in Norway and the United States. Contraception 2021 Jul 28;S0010-7824(21)00339-5. doi: 10.1016/j.contraception.2021.07.105. [Online ahead of print].