Detection of ovulation by changes in the color in the cervical mucus

Cervical mucus was aspirated daily in 11 adult Macaca fasicularis monkeys and in 70 women of reproductive age. Mucus was spread on a slide and dried at mild heat to observe crystallization. Another slide dried in the same way was heated in the flame of an alcohol lamp. The resulting colors ranged from dark brown to clear. Brown appeared immediately after menstruation becoming clearer as the cycle progressed until 1 day in mid-cycle was characterized by clear mucus. Mucus thereafter became brown again. These color stages corresponded to stages of crystallization. Results of laparotomy examination of ova and LH radioimmunoassay in macacas and of vaginal cytology basal temperature endometrial biopsy and radioimmunoassay of LH estradiol and progesterone in women suggest that ovulation occurs when the heated mucus has the lightest (clear) color.(AUTHORS MODIFIED)