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Even Best Contraceptive Methods Can Fail

Unplanned Pregnancies Sometimes Occur Among Birth Control Users
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WebMD Health News

April 29, 2003 -- Millions of women get pregnant each year despite regular use of contraceptives. Even the best contraceptive methods often fail, a new study shows, because they do not suit the individual user's circumstances.

Two-thirds of the women who had unplanned pregnancies in the French study reported using contraceptives, with one in five users taking the pill and one in 10 using intrauterine devices (IUDs). Lead investigator Nathalie Bajos, PhD, says even though these are two of the most effective contraceptive methods available, they were a poor choice for many of the women.

"What this research shows most clearly is that there is often a mismatch between a woman's contraceptive needs and the methods they use," Bajos says. "It is absolutely essential to differentiate between what are the theoretically most effective methods of contraception and what is the most practical method for a particular woman at a particular time in a particular relationship."

Several years ago, the term French Paradox entered the public consciousness to describe the apparent contradiction of a low incidence of heart disease in a population eating a diet high in animal fats. Bajos says her investigation stemmed from a second French Paradox -- a relatively high abortion rate despite the most widespread use of contraception in Europe.

In a 1994 survey, 68% of French women of reproductive age reported some type of contraceptive use, compared with 64% of women in the United States. But abortion rates in the U.S. steadily declined with increasing contraceptive use during the 1990s, and they have remained stable in France.

"We knew through previous studies that the rate of unwanted pregnancies was quite high, but we didn't have much information on individual contraceptive methods or why those methods failed, Bajos tells WebMD.

In the study, published in the latest issue of the journal Human Reproduction, Bajos and colleagues surveyed 1,034 women who reported having had an abortion or unintended pregnancy and 1,829 women who acted as a control group. The participants were taken from a representative sample of 14,700 households randomly selected from the telephone book.

The researchers found that 97% of the sexually active, reproductive-aged women who did not want to conceive used contraception. But 33% of all pregnancies were unplanned, and 65% of unplanned pregnancies occurred among women using contraception.

Oral contraceptive users accounted for 21% of the unwanted pregnancies in the women surveyed, while 9% of such pregnancies occurred among IUD users, 12% among condom users, and 23% among users of other contraceptive methods, such as male withdrawal or avoiding sex on fertile days.

Misuse of the contraceptive methods used was the main reason given to explain the unplanned pregnancies, with 60% of pill users saying they had forgotten one or more pill. More than half of women whose unplanned pregnancies occurred while using condoms said the condom slipped or tore during sex, and 30% said they did not use it on the occasion in which they got pregnant.

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