Following menstruation there will often be a number of days when you feel dry and don't see any discharge. This is called the Basic Infertile Pattern (BIP). We know from the work of scientists that the hormone levels are low at this time and the cervix is blocked by a thick plug of mucus which prevents sperm entering the uterus. This means that you're infertile at this time.
In the other common type of BIP there is an unchanging pattern of discharge following menstruation: the discharge feels and looks the same day after day. Again, the hormone levels are low and the cervix is blocked, resulting in infertility throughout this time.
This infertile pattern of dryness or discharge may continue for a few days, or even for weeks or months when ovulation is delayed (for example, while breastfeeding). Your Billings Ovulation Method® tutor will help you interpret your Basic Infertile Pattern so that you can apply the Early Day Rules with confidence.