The first indication of potential fertility will be a change from the Basic Infertile Pattern (BIP). You will feel a change in the sensation that the mucus produces at the vulva. As the days pass you'll notice that the mucus becomes thinner and clearer, and the sensation becomes wet and then slippery. Women use different words to describe this changing, developing pattern, but the mucus will always have a wet, slippery quality because of its chemical structure and composition, even when there is too little to see. This mucus is essential for fertility, and keeps sperm alive and healthy.
Changing Pattern of Fertility: You can see a group of follicles developing in the ovaries. Each follicle contains an ovum (egg) and a bundle of surrounding cells that secrete the hormone oestrogen. Oestrogen activates your cervix to produce the mucus essential for fertility. One type of mucus produced by the cervix dissolves the plug, which means sperm can now enter the uterus. Another type of mucus filters out damaged sperm cells. Yet another type nourishes the sperm so they can live for up to five days in your reproductive system. It forms channels which help the sperm travel through your reproductive system to meet and fertilise the egg.
The fertile phase begins with the change from the BIP and develops for an average of five to six days. But even if it only lasts for a day or so, it will warn you of the approach of ovulation and the need to avoid sex and intimate genital contact if you want to prevent pregnancy. And if you want to achieve pregnancy, recognising your developing fertility and the approach of ovulation helps you optimise your chances of conceiving.
You may also notice that the slippery sensation is accompanied by a feeling of fullness, softness or swelling of the tissues of the vulva. Many women described it as a feeling of “ripening” – something they can associate clearly with fertility. No other signs of fertility, such as pain or spots of blood, are as precise or as reliable as the mucus.