Hi, I was just wondering if it is possible that birth control pills can Change or postpone a period a menstrual cycle on a first months use because me and my girlfriend had protected sex a few days before she went on the pill and the 2 more times that same week. All times were used with a condom and reapplied After ever ejeculation. She was supposed to get her usual period a couple days ago and she's been on birth control for almost 3 weeks now. I really don't think sees pregnant because we used precautions and checked the condoms for holes afterwards and found nothing. So is it possible that she just has a new menstrual cycle and may come in a week or so???