Jan. 27 (UPI) -- Hormonal intrauterine devices are just as effective as their copper and plastic counterparts at providing emergency contraception and preventing unwanted pregnancies, a study published Wednesday by the New England Journal of Medicine found.
Just one woman out of 317 who received an IUD that releases the hormone progestin became pregnant after one month of use, the data showed.
Copper IUDs such as ParaGard are not treated with hormones and have been shown to prevent pregnancy for up to 10 years, according to the researchers.
In this study, none of the 321 women given copper IUDs became pregnant within one month of use, the researchers said.
"These findings support using hormonal IUDs as a safe and viable alternative for women seeking to prevent pregnancies up to five days after intercourse," study co-author Dr. David Turok said in a statement.
"As an emergency contraceptive, it appears to be no worse than a copper IUD and is way better than the morning-after pill," said Turok, an associate professor of obstetrics and gynecology at University of Utah Health.
"And, unlike emergency contraception pills, hormonal IUDs can continue to provide highly effective contraception for up to seven years," he said.
IUDs prevent pregnancy by stopping sperm from reaching and fertilizing eggs in the uterus. Most are shaped like a "T" and are about the size of the quarter, so that they can be implanted in the uterus, the organization said.
Five types are available in the United States, including four -- Kyleena, Liletta, Mirena and Skyla -- that release small amounts of progestin, the same hormone used in many birth control pills, according to the Utah researchers.
The fifth, the copper IUD, is hormone-free and is designed to trigger the immune system to prevent pregnancy, they said.
For this study, Turok and his colleagues recruited more than 700 women, age 18 to 35, who were seeking emergency contraception at six Utah Planned Parenthood clinics.
Of these women, 638 completed the study, 317 of whom were given a hormonal IUD and 321 who received a copper device, according to the researchers.
All of the participants had unprotected intercourse at least once in the previous five days.
In addition, they had regular menstrual cycles, knew the date of their last menstrual period, had a negative urine pregnancy test, wanted to prevent pregnancy for at least a year and were interested in using an IUD, the researchers said.
After one month, 0.3% of the women who used the hormonal IUD were pregnant, the data showed.
The risk for pregnancy with the so-called "morning-after pill," an oral emergency contraceptive medication, is about 2%, Turok said.
The risk for pregnancy with copper IUDs is about 0.1%, he said.
Using hormonal IUDs could have dramatic effects on emergency contraception, including reducing menstrual bleeding and cramping associated with copper IUDs, according to Turok and his colleagues.
"This is all about increasing access and options for people," Turok said.
"It's about supporting their opportunity to live the life they want and have meaningful sexual relationships in ways that are not tied to pregnancy," he said.