The most common methods for preventing pregnancy, according to a new government report are female sterilization, oral contraception, long-acting reversible contraception such as IUDs and implants, and male condoms.
To help understand fertility patterns across demographics, researchers combed through the latest data from the National Survey of Family Growth to study contraceptive use among women.
The results, published Wednesday by the US Centers for Disease Control and Prevention's National Center for Health Statistics, found that of the more than 5,500 respondents from 2015 to 2017, nearly 65% of women ages 15 to 49 reported using some sort of contraception in the month they were interviewed.
That's a slight increase since the previous report , which found that 61.6% of those surveyed used contraception from 2011 to 2015.
The most common contraceptive method reported was female sterilization, or tubal ligation, a surgical procedure in which the fallopian tubes are closed to prevent pregnancy. Of those surveyed, 18.6% said they've done so.
That's an increase from 14.3% of women from 2011 to 2015.
But that number is very much tied to age. Nearly 2 in 5 women ages 40 to 49, or more than 39%, relied on their sterilization for contraception. For women 30 to 39, the figure was about 1 in 5, or more than 21.5%. And for women 20 to 29, only 1 in 20, or about 4%, had had a tubal ligation.
"Sterilization has been a common form of contraception both due to its permanence and ability to have it done after delivery of a child when someone is already getting health care," Dr. Kristyn Brandi, an obstetrician-gynecologist and board member for the advocacy group Physicians for Reproductive Health, wrote in an email. "Many poor women may not have access to contraception outside of a childbirth (where emergency insurance is often obtainable) so may want something convenient and long lasting."
The second most common contraceptive method was the birth control pill. About 12.6% of women reported relying on the pill as contraception.
That's a decrease from 15.9% from 2011 to 2015.
The new report found that the pill, as it's known, was most popular among women 20 to 29 (19.5%), followed by those 15 to 19 (16.6%) and then 30 to 39 (11%), followed by only slightly more than 5% of women 40 to 49.
"The pill and permanent sterilization for women have been the most common method of contraception since 1982, according to the Guttmacher institute," wrote Dr. Lillian Schapiro, an Atlanta gynecologist in private practice, in an email.
Long-acting reversible contraceptives, including intrauterine devices and contraceptive implants, were used by 10.3% of respondents, making them the third most common method.
This is an increase from 2011 to 2015, when they were used by 8% of those surveyed.
The new report found use was highest for women ages 20 to 29 (13.1%), followed by those 30 to 39 (11.7%). More than 8% of respondents 15 to 19 used these methods, while less than 7% of women 40 to 49 did.
"LARC's are very safe now and becoming much more accepted," Schapiro wrote. "For women not ready to permanently prevent pregnancy they are a great option since they don't require remembering a pill every day and keeping up to date on a prescription."
Male condoms were the fourth most common method, used by 8.7% of those surveyed.
That's a decline from 9.2% of respondents reporting use from 2011 to 2015.
Now, women 20 to 29 and 30 to 39 used condoms the most: 11.6% and 10.6%, respectively. Just more than 5% of respondents 15 to 19 and 40 to 49 relied on condoms for contraception.
Male sterilization, or vasectomies, was relied on by 5.9% of women. That's an increase from 4.5% of those surveyed from 2011 to 2015.
Depo-Provera (a birth control shot), the contraceptive ring or the patch accounted for 3.2% of used methods. And all other methods were used with 5.6% of women.
"The pill and sterilization are our oldest forms of birth control and women are more familiar with them, so many women use what they are familiar with. However, as newer devices come unto the market and become popular, that may change," Brandi said.
The new report found that contraceptive use went up with age, with 37.2% of women 15 to 19, 61.9% of those 20 to 29, 72% of women 30 to 39 and 73.7% of women 40 to 49 using contraception.
Contraceptive pill use was highest among non-Hispanic white women (14.9%); 9.2% of Hispanic women and 8.3% of non-Hispanic black women reported relying on the pill.
Condom use and long-acting reversible contraceptive use, across racial backgrounds, did not differ with any significance.
Education levels also made a difference in what methods women used. The higher the level of education, the less likely a woman was to rely on sterilization. Of women who were sterilized, 41.9% had no high school diploma or GED, 32.1% had a high school diploma or GED, 23.7% had some college education, and 11.3% had a bachelor's degree or more.
Conversely, use of the pill went up according to education levels. Of those who relied on contraceptive pills, 4.9% had no high school degree or GED, 7% had a high school degree or GED, 10.1% had some college, and 16.3% had a bachelor's degree or more.
"It is important to understand what certain demographics are using so we understand their preferences and make sure that everyone has access to all forms of contraception," Brandi noted.
The 35% of women who were not using contraception when they were interviewed were either not sexually active (17%), were pregnant, were postpartum or were looking to get pregnant (7.5%), nonusers of contraception who'd been sexually active (7.9%) or nonusers for other reasons, like nonsurgical sterility (2.7%).