d by an health care professional.
             It can be very confusing trying to figure out what these numbers mean. Contraceptive effectiveness is usually reported as a percentage. These different effective numbers represent success in "women-years." So if a form of birth control is 98 percent effective, that means that, on average, 98 out of 100 women using it for one year will not get pregnant. Occasionally, contraceptive effectiveness is reported in terms of "failure rates." So in the above content, the same form of birth control would have a 2 percent failure rate, meaning that 2 out of 100 women using this form of birth control would get pregnant in the period of one year. You also often see two numbers reported for each form of birth control, ideal and typical. Ideal represents the level of effectiveness if used perfectly every time; typical rates take into account human failure. Here's
             a neat trick: you can compute the effectiveness of combining two forms of birth control by
             multiplying the numbers. So for example, if you combine a condom (12 percent typical failure
             rate) with spermicidal foam (21 percent typical failure rate), the failure rate plummets to 2.5
             Most people think that the timing of taking the pill is impo
             ...