Cervical mucus and identification of the fertile phase of the menstrual cycle.

Nine healthy fertile women were studied during 29 menstrual cycles. A cervical mucus grading system, assessed by the patient and used in conjunction with basal body temperature, was correlated with plasma levels of luteinizing hormone (LH), oestradiol and plasma progesterone. The results show that a patient can be taught to predict the time of ovulation by observing the changes in the cervical mucus.