Chances of getting pregnant after taking the plan b pill on the last day of your period? how accurate are pregnancy tests 3 weeks after taking plan b

Pregnancy unlikely: Taking Plan B or other emergency contraception pills can alter the timing or the quality of the current menstrual cycle and the upcoming cycle. One should check a urine pregnancy test 3 weeks after taking Plan B, because emergency contraceptive pills work most of the time but not all of the time. Tests are very accurate 3 weeks after sex.