emergency contraception
"I just wanted to share my experience in case any of you are experiencing a delayed period after taking EllaOne. I had unprotected sex on the 8th of November, and I was on the pill but I really hadn't taken it properly that month, I got EllaOne and took it about two hours after the unprotected sex. 
I was due my period the following Monday but it never came. I had extremely light spotting and cramps, I freaked myself out thinking this was implantation bleeding and took multiple tests which were all negative.
My period for that month didn't come, even though the doctor I went to about a separate issue said this wasn't possible. 
My period finally came today, 3 weeks and 4 days late! try not to worry, I drove myself crazy about it for no reason!"