Cervical Changes
By doing self examinations of the cervix a woman may note changes in the cervix that correspond to her observations of cervical mucus days and dry days.
During the infertile phases of the cycle (dry days), under the influence of progesterone, the cervix is closed, firm (firm like the tip of the nose) and tilted toward the rectum. As estrogen levels rise and mucus begins to be produced (fertile days) the cervix opens slightly to allow mucus to flow through.
As the cervix opens it becomes softer (soft like lips) and its position becomes straighter up and down until it is very near vertical at ovulation.
These subtle changes observed over several cycles become another reliable symptom for determining fertility or infertility. This symptom is usually employed in situations like breastfeeding, and continuous mucus (see Chapter 7).