A recent TV add for an oral contraceptive stated that it was 99% effective. How is that measured? I believe that the average married couple has sex about 100 times a year. Does that mean she can expect to get pregnant after a year of normal sex? Obviously not, so what do they mean: 99% effective.
Just a WAG. When they finally tested it on human subjects, 1% of the women who took it got pregnant anyway.
I believe the percentage applies to a year of sexual activity, not to each sexual encounter. That is, the average sexually active woman on the pill has a 1% chance of becoming pregnant within the year.
Lamia’s right, it’s the percentage of people using the contraceptive who get pregnant over the course of the year. I don’t think it adjusts for how much sex you have, but it also doesn’t adjust for people using it incorrectly. (So if you miss a day or two, and get pregnant, that still counts against the pill’s accuracy.)
-LV
The master speaks:
What does it mean when they say The Pill is “99% effective”?
Good work and welcome aboard, tc.
My first car was nicknamed tc. So I’ll be watching your career here with no small amount of interest. 