Getting period after taking plan b

[Sundropz]

Hi. I had an accident last week and needed plan b. I took it within 12 hours. My birth control failed and I had 2 pills left. The doctor told me to expect my period at the normal time ( it was due yesterday) but still it's not here. I took a pregnancy test and it was negative. I'm worried that when I start my new pill pack on Tuesday my period won't come at all.

[Mo]

I'm a bit surprised your doctor said to expect your period at the normal time, to be honest! A very common side effect of Plan B is that it can cause some irregularities in your cycle for a few months. Because of this, we do recommend that people take a pregnancy test after needing emergency contraception, since it's not always possible to rely on a period coming when expected. A week after the risk is a bit too soon to test, so you could take another one in a week or two if that would ease your mind a bit (the test packaging should have info on how soon after a risk you can take it for best results).

[Sundropz]

Thank you. The box said I could take the test up to 3 days before my period is due I don't know if this makes a difference.

[Mo]

The reason it may have been too early to test is that a pregnancy, when it happens, isn't instantaneous; it can take a few days between a pregnancy risk and the actual point that signals the start of a pregnancy. And after that, it takes a few days for the hormone that pregnancy tests pick up to be at levels that will be detected; often a week from risk to test just isn't long enough. So, if you're feeling worried in a week or so you could try another test. We have some more info on tests, how they work, and when to take them here: Peeing on a Stick: All About Pregnancy Tests