A new study has found that shorter-acting methods of birth control, such as the Pill and the contraceptive patch, are much less effective at preventing unintended pregnancies than long-acting birth control methods such as intrauterine devices, or IUDs, and implants.
There are approximately six million pregnancies in the U.S. each year, and about half of them are unplanned. Approximately half of the unintended pregnancies are due to contraceptive failure, especially among younger women who use short-acting birth control methods. These include the Pill, which must be taken daily, and the hormone patch, which women must remember to change on a regular basis.
Jeffrey Piepert, a professor of obstetrics and gynecology at Washington University School of Medicine in St. Louis, Missouri, says experts knew that so-called longer-acting reversible contraceptives, or LARC (LARK) methods, offered better protection against pregnancy than the Pill or the patch.
"What we didn't expect was the magnitude of the difference. There were 20-fold greater number of contraceptive failures in the Pills, patch and ring group compared to the LARC methods," said Piepert.
The finding was based on a study by Washington University researchers comparing long-acting contraceptive methods to short-acting ones.
LARC methods of contraception include the intrauterine device, or IUD, and hormone-releasing implants. There are two types of IUDs; one releases tiny amounts of hormone over a period of years that prevents conception and the other contains copper that makes the uterus inhospitable to fertilized embryos. The copper IUD can remain in place for up to ten years. Implants, just beneath the skin, contain hormones that prevent ovulation. Both IUDs and implants must be put in place by a health care professional.
The study involved 7,500 women between the ages of 14 and 45 who were sexually active or wanted to become active, but didn't want to become pregnant for at least 12 months.
Over the course of the three-year study, 334 women became pregnant, including 156 pregnancies due to contraception failure. Of these, 133 women were using the Pill, patch or vaginal ring, compared to just 21 who had been using IUDs or implants for years.
Peipert, in an interview with Washington University's Jeff Dryden, says it's clear why LARC methods are the most effective forms of contraception. "One they are put in place, you don't have to remember to change a ring or change a patch or take a pill everyday. Any method that relies on adherence or compliance is subject to failure."
The U.S. National Institutes of Health estimates that 150 million women worldwide use the copper IUD, which is inexpensive and easily removed.
An article comparing the effectiveness of long-acting to short-acting contraceptive methods is published in the New England Journal of Medicine.