| Abstract: | The ovulation method of family planning relies on self-recognition of physiological changes occuring around time of ovulation rather than a calendar to enable a couple to avoid sexual intercourse during the fertile period. The most practical signs are elevated basal body temperature, changes in the amount and physicochemical properties of cervical mucus, and ovulation pain. The basal body temperature rises about .3 degrees C following ovulation. The problem with this method is that it is retrospective. The mucus symptoms, as described by Billings and associates in Melbourne, Australia, are: 1) a variable number of days with no vaginal discharge following menstrual bleeding; 2) onset of mucus symptoms characterized by increasing quantities of 'cloudy' or 'sticky' secretion; 3) a clear, slippery lubricative mucus having the characteristics of raw white of egg (spinnbarkeit), which is an immediate forwarning of ovulation; 4) a variable period of thick, opaque, diminished volume discharge followed by dry days. The clear 'peak symptom' mucus lasts 1-2 days; in a study of 22 women followed for 27 cycles this symptom occurred .9 days +3 or -2 days before ovulation. The problem is that 2 of the 22 cycles reported in detail had ovulation 3 days after the peak symptom and 1 had ovulation 4 days after. Intercourse on the 4th day, therefore, would have had a significant risk of pregnancy. Weissman and associates collected data on 282 women on the Pacific island of Tonga who used the mucus symptoms alone to control conception. In the 2503 cycles there were 53 unplanned pregnancies, 25.4 per 100 woman-years using the Pearl formula. 50 resulted from the couples 'taking a chance,' 2 misunderstood the method, 28 abandoned the method because they wanted more children, and 1 woman became pregnant even though she thought she understood the method. Field trials with groups who are more motivated than those in the Tongan trial are needed. |
