I had to cancel our IVF cycle but only after I took three days of the 'pill'. My next period was three days late but normal. I wasn't due for the next period for another 8/9 days but it arrived yesterday with vengeance. Any idea why? I wouldn't think three days of the pill would do this. I'm normally like clockwork. Prior to fertility treatment I was on the pill for 20 years and never had an issue.