A copper intrauterine device was 100 percent effective at emergency contraception in a study of almost 2000 Chinese women who had the device implanted up to 5 days after unprotected sex.

The device - called Copper T380A, or Copper T - continued to be effective at preventing pregnancy a year after it was inserted.

“It is by far the best emergency contraceptive option,” Dr. James Trussell, who studies birth control methods at Princeton University but was not involved with the current study, told Reuters Health of the device. “But many people just don’t know about it.”

Copper T, marketed as ParaGard in the United States, is a T-shaped piece of flexible plastic wrapped in a layer of copper that is inserted into the uterus. It works by stopping sperm from reaching the egg and by preventing an embryo from implanting in the wall of the uterus.

Led by Dr. Shangchun Wu at the National Research Institute for Family Planning in Beijing, China, the authors followed almost 2000 Chinese women who were implanted with the Copper T after coming into family planning clinics for emergency contraception. All of the women had engaged in unprotected sex in the previous 5 days.

Women came back to the clinic for follow-up visits 1, 3, and 12 months after the device was implanted.

Of women who came back for their first follow-up visit - all but 70 - none had gotten pregnant.

About three-quarters of the women came back to the clinic a year after having the Copper T inserted and still had it in. Four women had gotten pregnant while the device was still in over the course of the year.

Over that year, about 100 women had the device removed, either because it had partially come out on its own or they were having side effects, such as heavier or more uncomfortable periods.

Copper T is mainly used in the United States for long-term birth control, and can be left in for up to 10 years. While the device is Food and Drug Administration approved for regular contraception, doctors can use it off-label for emergency contraception, Trussell said. On its women’s health site, the Department of Health & Human Services lists intrauterine devices as a valid form of emergency contraception.

Doctors in Rhode Island are currently under investigation for implanting hundreds of women with cheaper, non-approved versions of Copper T and another type of intrauterine device, Mirena.

Before this study, said Dr. Emily Godfrey, one of the paper’s authors from the University of Illinois Medical Center, there were signs from smaller studies that Copper T might work well as an emergency contraceptive, but “we just didn’t have evidence with large numbers of trials,” she told Reuters Health.

Previous studies estimated that among women who had the device inserted within 5 days of unprotected sex, about 1 in 1,000 would get pregnant, Godfrey said. Her team’s findings suggest it could be even more effective than that.

Plan B, the over-the-counter pill used for emergency contraception, advertises that 1 in 100 women will get pregnant if they take it within 3 days of unprotected sex.

Yet despite the benefits of Copper T, it’s not easy to get for many women seeking emergency contraception in the United States. One deterrent is that while women 17 and over can buy Plan B over-the-counter at a pharmacy, Copper T must be inserted by a doctor - an extra step for women who only have a window of time when emergency contraception can work.

“The issue,” Godfrey said, “is immediate access. In the U.S. it’s easier just to go to a pharmacy.”

And while Plan B runs for about $50 off the shelf, Godfrey said that depending on her insurance a woman could pay more than $500 to have Copper T inserted. “Cost could certainly be prohibitive,” she said.

But, “you get great bang for your buck,” Trussell said. Unlike Copper T, “if you take emergency contraception pills today, they’re not going to protect you against unprotected sex next week,” he said.

Dr. Suzan Goodman, who has studied the use of Copper T, said that some women might still be influenced by “lingering misperceptions” of the safety of intrauterine devices. But Copper T is not like the devices that caused infection in the 1970s, said Goodman, of the University of California, San Francisco. Instead, it’s “extremely safe.”

“It’s too bad it’s not used more often,” Trussell said of Copper T. “If there were many, many more IUD insertions rather than emergency contraception pills (used), it certainly would have an impact on lowering pregnancy rates and abortion.”

SOURCE:  BJOG: An International Journal of Obstetrics and Gynaecology, online July 7, 2010.