it depends what studies you read, i suppose.
(from http://www.wprc.org/sexuality/faqcondoms.html)For adults, the failure rate is about 14% per year of use. That means every year about 1 in 7 condom users experience an unplanned pregnancy. For persons under the age of 18, condoms were found to have a failure rate of 18% over one year. For unmarried minorities, the condom failure rate is 36% per year, and for unmarried Hispanics, the failure rate is as high as 45% annually. Spermicidal condoms have not been proven more effective than the non-spermicidal type.
it depends on misuse and all sorts of things. as far as unplanned pregnancies go i think condoms are the worst, but a lot of the other methods have to protection against infection.
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