Detection of the fertile phase from changes in cervico-vaginal fluid volume.

Characteristic changes in cervico-vaginal fluid (CVF) volume which occur during the menstrual cycle might be used to detect the fertile phase. Twenty-five normal women were asked to withdraw CVF and measure its volume at home using a small, disposable, graduated vaginal aspirator. In 16 cycles day 0 (ovulation) was defined as the day of maximum follicular diameter according to serial ultrasound examination. A rise in CVF volume occurred between day -9 and -2 and a peak between day -4 and 0. In these sixteen, and in a further 72 cycles, day 0 (time of maximum fertility) was taken as the day of peak cervical mucus secretion. CVF volume rose, on the average, on day -6.2 (range -17 to -2) and peaked on day -0.8 (range -5 to +2). In two cycles, no rise and peak were identified. Changes in CVF volume were easy to recognise and could be useful to couples wishing to achieve pregnancy.