Since ancient times, women have tried to prevent unwanted pregnancies after unprotected intercourse. As early as 1500 B.C., they were advised to try sneezing, hopping, jumping or dancing. In early 20th-century America, the makers of Lysol and other household disinfectants and detergents advertised their effectiveness for “feminine hygiene.” Even douching with Coca Cola was rumored to interfere with conception, in the late 1960s.
Since the 1970s, however, physicians have known that large hormone doses taken soon after intercourse actually can prevent pregnancy. “Oral contraceptives have been used 'off label' as emergency contraception by at least 225,000 women in the United States,” according to the American Pharmacists Association.
But hormonal medicines have been specifically packaged as emergency contraceptives only in recent years. In 1998, the Food and Drug Administration (FDA) approved the Preven regimen. Then, in 1999, the FDA approved Plan B, a less potent, safer and more convenient product. The same manufacturer now owns both products and removed Preven from the U.S. market last year.
Although emergency contraception has been available in the United States for seven years, confusion is rife about what it is and how it works.
For instance, in California — where some pharmacists have been allowed to dispense emergency birth control without prescription since 2002 — about three-quarters of women ages 18 to 44 polled in 2004 had heard of emergency contraception, but nearly half confused it with abortion pills. Abortion pills, such as mifepristone — also known as RU-486 — were approved in Europe in the late 1980s, but opposition from religious conservatives and pro-life groups blocked their approval in the United States until 2000.
Mifepristone, which can be taken up to two months after a woman's last menstrual period, causes abortion by blocking the hormones needed to maintain a pregnancy. Methotrexate, which blocks further development of the pregnancy in the uterus, can be taken up to about six weeks after a woman's last period. To trigger contractions, the drugs are then taken in combination with misoprostol, which causes the uterus to contract and empty.
On the other hand, Plan B and other emergency contraceptive pills like Preven operate like regular birth-control pills — another point of confusion. In a 2003 survey of South Dakota pharmacists, 37 percent did not know that emergency contraceptive pills — now called Plan B — work basically the same as regular hormonal birth-control pills.
The mechanism by which emergency contraceptives prevent pregnancy is not completely understood, but, in general, they delay or prevent ovulation, inhibit fertilization of an egg and may sometimes alter the climate of the uterus to prevent a fertilized egg from implanting. If taken after implantation, emergency contraceptives cannot abort a pregnancy. (Implantation usually begins about five days after fertilization and can take up to 18 days.)
The question of whether emergency contraception prevents implantation of a fertilized egg — known among birth-control opponents as “the post-fertilization effect” — has triggered controversies around the country. The controversy primarily involves defining the moment at which life begins: Is it when the egg is fertilized or when the fertilized egg implants itself in the uterine wall?
Biomedicine has long defined the beginning of pregnancy as the time when the fertilized egg implants in the uterus. But the Catholic Church, some conservative Christians and others define it as “conception” — the moment when an egg is fertilized. These groups believe that emergency contraceptives — and even regular birth-control pills and intrauterine devices that prevent implantation — destroy life by causing early-stage abortions.
“Contraception is a misnomer in this case because [emergency contraception] commonly operates not to prevent conception but rather to ensure the death of an embryo after conception by interfering with implantation in the womb,” according to U.S. Conference of Catholic Bishops testimony to the Kansas legislature in 2002.
But not all Christian conservatives agree. It's difficult to argue that a non-implanted embryo constitutes a pregnancy, according to John Guillebaud, emeritus professor of family planning and reproductive health at University College, London, whose views are posted on the Web site of the Christian Medical Fellowship of the United Kingdom.
While the embryo is “free in the uterine cavity, it still has 100 percent 'No Go' status,” Guillebaud explained. “It is a certainty that in a few days it will be flushed through the cervix and vagina in a gush of endometrial debris and blood.” For instance, the mother's body does not receive signals to begin producing pregnancy-sustaining hormones until the egg implants, he pointed out.
Moreover, up to 50 percent of embryos fail to implant naturally, he added. “Now, we know that our God is omnipotent, omniscient and omnipresent,” Guillebaud continued. “How likely is it that a God, who surely has 'omni-common sense' . . . would expect us to give the status, importance and respect to this entity . . . as is rightly given after implantation — when there is a relationship with the mother and for the first time there are prospects of going to term?”
In any case, scientists may be on the verge of proving that emergency contraception has no post-fertilization effect after all. New studies on rats and monkeys — and a limited human study — have shown that emergency contraceptives do not inhibit implantation — a fact that could explain their 20 percent failure rate.