The research, published in today's edition of the Canadian Medical Association Journal, also shows that ready access to emergency contraception likely prevented hundreds of abortions in the province.
The new data come just days before it will become legal, from coast to coast, for women to purchase levonorgestrel (sold under the brand name Plan B) from a pharmacist without a doctor's prescription.
The drug will be kept behind the pharmacist's counter, however, rather than on the shelf. Proponents have praised the move to behind-the-counter status but continue to push for the drug to be sold, without restrictions, on pharmacy shelves.
The new study, conducted by Judith Soon of the faculty of pharmaceutical sciences at the University of British Columbia in Vancouver, found that women used emergency contraceptive rationally and promptly. They were also far more likely to get Plan B directly from a pharmacist than from a physician.
The vast majority of women sought the drug because of a contraceptive failure, such as a broken condom, and they were far more likely to do so when they were ovulating and their risk of pregnancy was highest.
The study found that almost 18,000 B.C. women used emergency contraception in 2002, compared with an average of 8,800 a year before the provincial government began to allow non-prescription sales two years earlier.
Almost 60 per cent of women sought emergency contraception from a pharmacist or doctor within 24 hours of unprotected intercourse, the study found, and that number rose to almost 90 per cent at 48 hours.
(Despite its nickname "morning-after pill," levonorgestrel can prevent pregnancy for up to 72 hours after intercourse, though effectiveness declines over time.)
The study also found that only 2 per cent of women used the drug repeatedly, allaying fears that Plan B might be used instead of prophylactic contraception such as condoms, diaphragms, IUDs or birth-control pills.
"Timely access to emergency contraception has the potential to reduce unwanted pregnancies and subsequent abortions," Dr. Soon said. She estimated that, over a two-year period, about 550 unwanted pregnancies were avoided in British Columbia with the sale of Plan B in pharmacies, pregnancies that most likely would have ended in abortions.
Plan B works exactly like a birth-control pill, but post-coitally. It capitalizes on the fact that conception does not occur immediately after ejaculation; it takes up to 24 hours for sperm to fertilize an egg and several more days for the egg to migrate into the uterus and latch on. The hormones in the pill make the uterus inhospitable. If a woman is already pregnant, however, there are no effects on the fetus.
An emergency contraception pill is not an abortion pill. But anti-abortion activists oppose the sale of Plan B in Canada, describing it as an "abortifacient." (RU-486, the so-called abortion pill, is not available in Canada.)
British Columbia allowed behind-the-counter sale of Plan B in 2000. Before that, it could be obtained with a doctor's prescription.
Doctors have also long suggested the so-called Yuzpe method, the prescription of a high dose of regular birth-control pills, as a form of emergency contraception.
Plan B, which is marketed in Canada by Paladin Labs Inc., costs about $25, and pharmacists charge another $20 or more as a consultation fee.
Health advocates, such as the Canadian Women's Health Network, argue that the drug is safe and should be sold over the counter. They say that a mandatory consultation with a pharmacist is unnecessary and that the cost discourages women from using the treatment.
In a strongly worded editorial, the Canadian Medical Association Journal agrees with that position, saying that the reclassification of Plan B as a non-prescription drug is good news, but that the drug should be available without restriction.
"The news would be better if a lingering paternalism in matters affecting women's reproductive health was not still hiding behind the counter," the editors wrote.
The CMAJ also argues that, if Plan B were more widely available, there is no doubt Canada's abortion rate would fall.
There were 105,154 abortions performed in Canadian hospitals and clinics in 2002, the latest year for which national figures are available, according to Statistics Canada. That means 15.4 of every 1,000 Canadian women 14 to 44 years old had an abortion in 2002, a rate that has remained stable since 1988, when therapeutic abortions were legalized after a Supreme Court of Canada ruling.
André Picard