"my husband and i have 3 kids and are very good about tracking my ovulation cycle to prevent pregnancy. this particular time we had sex my calculation was one day off. within 24 hours i caught the mistake and within 36 hours took the plan b pill. my period is like clockwork so when it didn&#039;t come, i gave it another week, and took a pregnancy test and i was pregnant. i think plan b just makes you think it worked but 9 times out of 10 most of the women who take it aren&#039;t aware of their ovulation cycle. i pay close attention to my body and when my period didn&#039;t come on the expected day i knew i had to be pregnant but waited it out to make sure. i would bet most women aren&#039;t even ovulating when they are taking plan b to ward off pregnacy."