Emergency Contraception: Clearing Up the Confusion

In Canada, two types of medications can be used to prevent pregnancy if there has been unprotected intercourse: oral contraceptives, a combination of commonly used hormones, or newer and better dedicated products containing only Levonorgestrel, a hormone found in some birth control pills. On May 18th, the federal government announced plans to make Levonorgestrel available without a physician’s prescription, as it already is in 31 countries and 5 US states. Canadian Bishops oppose the move. Ironically, the very pill they allege to cause abortion has tremendous potential to prevent over 100,000 abortions in Canada annually.

Hormones used as contraceptives cannot cause abortions. “Contra” “ception” prevents conception, not abortion. Oral contraceptives are the most commonly used form of birth control in Canada: the most recent Canadian Contraception Study (2002) found that 32% of women surveyed used oral contraceptives. If a woman is already pregnant, mistakenly taking oral contraceptives will not harm her or her baby. The same is true for emergency contraception.

Part of the confusion stems from the fact that, since 1869, the Roman Catholic Church has defined that human life begins at the moment of conception. Since then, science has determined that life begins as a cascade of many steps, beginning with ovulation, including fertilization and requiring several more events before a pregnancy occurs. Couples undergoing infertility treatment will be aware that the achievement of ovum fertilization in a petri dish does not constitute a pregnancy. The medical and legal definition of pregnancy is the completed implantation, and not the fertilization, of the blastocyst. A WHO Technical Report published in 1987 clarified that the process of implantation, beginning about 5-6 days post-fertilization, takes up until 13-14 days to be completed. In its 1998 definition of pregnancy, the International Federation of Gynecologists and Obstetricians (FIGO) states that pregnancy is the part of human reproduction “that commences with the implantation of the conceptus in a woman”.

Another part of the confusion may stem from the use of abortificients, such as RU 486 (mifepristone) and methotrexate available in some countries as emergency contraceptives. But the hormones being used here for emergency contraception in Canada are not and do not contain any substance even remotely similar.

If levonorgestrel is not able to provoke an abortion, how does it work? Large clinical trials conducted internationally have found that the mechanism of action depends on the timing. If taken before and up to ovulation, levonorgestrel appears to delay ovulation, or cause it to be dysfunctional. There is also some research evidence to suggest that levonorgestrel interferes with the migration and function of sperm. Taken after intercourse, researchers have noted that levonorgestrel causes changes in cervical mucous, alters the pH of the uterine fluid and reduces the number of sperm recovered from the uterine cavity. The previously held belief that levonorgestrel changes the endometrium and prevents implantation is not supported by research findings.

These findings support the results from trials showing that emergency contraception is most effective if taken within the first 24 hours of unprotected intercourse. A recent Ontario pilot study found that most young women calling a hotline for EC did so within the first 24 hours. These results underscore the reason for making levonorgestrel available from a pharmacist without a prescription: early access is critical. This is even more important for adolescents, who, despite parental taboos and cautionary sexual health programs, are at highest risk of having unprotected intercourse.

Dr Andre Lalonde, the Vice-President of the Society of Obstetricians and Gynecologists of Canada told the Canadian Medical Association Journal “If you are against abortion, this is a wonderful pill”. Levonorgestrel is already available behind-the-counter in BC, Quebec and Saskatchewan.

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