Fertil Steril. 1981 Aug;36(2):152-8.
The percentage of 869 women in five countries capable of being taught to recognize the periovulatory cervical mucus symptom of the fertile period was determined in a prospective multicentre trial of the ovulation method of natural family planning. The women were ovulating, of proven fertility, represented a spectrum of cultures and socioeconomic levels, and ranged from illiteracy to having postgraduate education. In the first of three standard teaching cycles, 93% recorded on interpretable ovulatory mucus pattern. Eighty-eight per cent of subjects successfully completed the teaching phase; 7% discontinued for reasons other than pregnancy, including 1.3% who failed to learn the method. Forty-five subjects (5%) became pregnant during the average 3.1-cycle teaching phase. The average number of days of abstinence required by the rules of the method was 17 in the third teaching cycle (58.2% of the average cycle length). To what extent the findings of this study can be extended to other couples remains to be demonstrated.
在一项关于自然计划生育排卵法的前瞻性多中心试验中，确定了五个国家中869名能够被教会识别排卵期宫颈黏液症状的女性的比例。这些女性正在排卵，生育能力已得到证实，代表了不同的文化和社会经济水平，从文盲到拥有研究生学历。在三个标准教学周期的第一个周期中，93%的人记录了可解释的排卵黏液模式。88%的受试者成功完成了教学阶段；7%因非怀孕原因中断，包括1.3%未能学会该方法的人。45名受试者（5%）在平均3.1个周期的教学阶段怀孕。该方法规则要求的平均禁欲天数在第三个教学周期为17天（占平均周期长度的58.2%）。本研究结果能在多大程度上推广到其他夫妇还有待证明。
