yes it's quite possible. Your period is the shedding of the uterin buildup that happens while it's preparing for the possibility of pregnancy. When that doesn't happen, then that extra stuff sheds and that is why you bleed and have your period.Ovulation Calculator is a easy and simple to use application to calculate the actual time of ovulation and determine the fertile period.
This is best to check with your doctor. Many women fall pregnant when taking some antibiotics or other medicines that make the pill less effective, this may have an effect on your system and best to find out all the side effects. A lot of pharmacists can print out a booklet of all possible side effects, as well, your pharmacist may be able to help you right away