Trials of the ovulation method of natural family planning

PIP: The concept of utilizing changes in cervical secretion offers a potentially simple method of natural family planning. A detailed international trial has been conducted to test the effectiveness of the method. 5 centers are involved: Auckland; Bangalore; Dublin; Manila; and San Miguel. The observations provide an indication of the value and success of the method. They also reveal interesting variations between the different centers and between various socioeconomic classes. The work was divided into a teaching phase and an effectiveness phase. The initial phase was designed to teach individual women how to recognize the symptoms in cervical mucus, and it usually covered the first 3 complete cycles. The subjects were ovulatory, of proven fertility, less than 39 years, nonlactating, and with a history of a menstrual cycle of between 23 and 35 days. Data were collected from the patient and returned to the organizers for analysis. Comparisons were then made between different centers on the 2 study phases. In the teaching phase 94% of the women could soon recognize and record their own cervical mucus symptoms. Many women could understand the principle of the method within the 1st teaching cycle. Almost 90% of the subjects completed the teaching phase, and 7% discontinued for various reasons, including 1.3% who failed to learn the method, and 5% who became pregnant. The average number of days of abstinence by the method was 17 in the 3rd teaching cycle, a high proportion of the length of the average menstrual cycle. After the teaching phase, 725 subjects were studied in an effectiveness phase which lasted for 13 cycles. More than 7500 cycles were analysed. High rates of method failures were found in the 2 most socially developed centers, Auckland and Dublin. Pearl rates for method failure ranged from 9.4/100 women years in Auckland to 1.1 in Manila and 0 in Bangalore and San Miguel. The accumulative probability of discontinuation after 13 cycles was 35.6%, more than half of this figure being due to pregnancy. Detailed pregnancy rates/100 woman years, using the modified Pearl Index, were found to be as follows: conscious departure from the rules of the method, 15.4; inaccurate application of instructions 3.5; method failure 2.8; inadequate teaching 0.4; and uncertain reasons 0.5. Subjects were not selected randomly.