A study to evaluate birth-control methods has found
dramatic differences in their effectiveness. Women who used short-term methods like birth-control pills, the patch or vaginal ring were 20 times more likely to
have an unintended pregnancy than those who used longer-acting forms
such as an intrauterine device (IUD) or implant.
Results of the
study, by researchers at Washington University School of Medicine in St.
Louis, are reported May 24 in the New England Journal of Medicine.
Birth-control pills are the most commonly used reversible contraceptive in
the United States, but their effectiveness hinges on women remembering
to take a pill every day and having easy access to refills.
the study, birth-control pills and other short-term contraceptive
methods, such as the contraceptive patch or ring, were especially
unreliable among younger women. For those under 21 who used birth-control pills, the patch or ring, the risk of unplanned pregnancy was
almost twice as high as the risk among older women. This finding
suggests that increased adolescent use of longer acting contraceptive
methods could prevent substantially more unplanned pregnancies.
study is the best evidence we have that long-acting reversible methods
are far superior to the birth-control pill, patch and ring,” says senior
author Jeffrey Peipert, MD, the Robert J. Terry Professor of Obstetrics
and Gynecology. “IUDs and implants are more effective because women can
forget about them after clinicians put the devices in place.”
pregnancy is a major problem in the United States. About 3 million
pregnancies per year — 50 percent of all pregnancies — are unplanned. The
rate of unintended pregnancy in the United States is much higher than in
other developed nations, and past studies have shown that about half of
these pregnancies result from contraceptive failure.
inserted into the uterus by a health-care provider. The hormonal IUD is
approved for five years, and the copper IUD can be used for as long as 10
years. Hormonal implants are inserted under the skin of the upper arm
and are effective for three years. Many women, however, cannot afford
the upfront costs of these methods, which can be more than $500.
know that IUDs and implants have very low failure rates — less than 1
percent,” says Brooke Winner, MD, a fourth-year resident at
Barnes-Jewish Hospital and the study’s lead author. “But although IUDs
are very effective and have been proven safe in women and adolescents,
they only are chosen by 5.5 percent of women in the United States who
Earlier contraceptive studies asked women to
recall the birth-control method they used and number of pregnancies. For
this study, the investigators wanted to determine whether educating
women about the effectiveness of various birth-control options and
having them choose a method without considering cost would reduce the
rate of unintended pregnancy. Birth control was provided to women at no cost.
The study involved more than 7,500 women enrolled in the
Contraceptive CHOICE project. Participants were ages 14-45 and at high
risk of unintended pregnancy. The women were sexually active or planned
to become sexually active in the next six months. They either were not
currently using contraception or wanted to switch birth-control methods.
The women also said they did not want to become pregnant for the next
Participants in this report could choose among the
following birth-control methods: IUD, implant, birth-control pills,
patch, ring and contraceptive injection. The women were counseled about
the contraceptive methods, including their effectiveness, side effects,
risks and benefits. Participants were permitted to discontinue or switch
methods as many times as desired during the study.
interviewed participants by telephone at three and six months and every
six months thereafter for the remainder of the study. During each
interview, participants were asked about missed periods and possible
pregnancy. Any participant who thought she might be pregnant was asked
to come in for a urine pregnancy test. Those who were pregnant were
asked if it was intended and what contraceptive method, if any, they
were using at time of conception.
Over the three-year study, 334 women became pregnant. Of these, 156 pregnancies
were due to contraceptive failure. Overall, 133 (4.55 percent) of women
using pills, the patch or ring had contraceptive failure, compared with
21 (0.27 percent) of women using IUDs and implants.
also is important because it showed that when IUDs and implants are
provided at no cost, about 75 percent of women chose these methods for
birth control,” Winner says.
Women who chose an IUD or implant
were more likely to be older, to have public health insurance and to
have more children than women who chose other contraceptive methods.
Women who chose pills, the patch or ring were more likely to have
private health insurance and to not have had children previously.
“If there were a
drug for cancer, heart disease or diabetes that was 20 times more
effective, we would recommend it first,” he says. “Unintended
pregnancies can have negative effects on women’s health and education
and the health of newborns.”
B, Peipert J, Qiuhong Z, Buckel C, Madden T, Allsworth J, Secura G.
Effectiveness of long-acting reversible contraception. New England
Journal of Medicine. Vol. 366. May 24, 2012.
School of Medicine’s 2,100 employed and volunteer faculty physicians
also are the medical staff of Barnes-Jewish and St. Louis Children’s
hospitals. The School of Medicine is one of the leading medical
research, teaching and patient care institutions in the nation,
currently ranked sixth in the nation by U.S. News & World Report.
Through its affiliations with Barnes-Jewish and St. Louis Children’s
hospitals, the School of Medicine is linked to BJC HealthCare.