Persons we corresponded with were influenced by the work of Dr. Edward F. Keefe. Over 40 years ago, two breastfeeding mothers corresponded with me about how helpful the cervix sign was in determining the return of fertility during breastfeeding amenorrhea. At that time I had published (in mimeograph form) the first edition of Breastfeeding and Natural Child Spacing. Because of this book, the mothers wanted to share their experiences with me. One of those mothers conceived once without a period during breastfeeding amenorrhea. In another breastfeeding experience, she found the cervix sign invaluable in determining the return of fertility with her nursing 15 month old baby. Again her fertility returned during breastfeeding amenorrhea, but she observed the return using the cervix sign. She was charting the mucus sign but the cervix sign was more helpful at that time. As a result of my correspondence with those mothers, we felt obligated to teach the cervix sign. These mothers were influenced by Dr. Keefe’s work.
John and I taught the cervix sign and the internal mucus exam when we first started teaching NFP in 1971. These two fertility signs were taught in our first teaching manual, The Art of Natural Family Planning (1972). I remember years ago being at an NFP gathering when the women began discussing how great the internal mucus exam was. One woman did not know where she was in her cycle, tried the internal mucus exam and found it to be very helpful. She was raving about this sign and got the discussion started.
I encourage other couples who have a sufficiently serious reason to postpone pregnancy to consider learning these two signs, the internal mucus exam and the cervix exam. These signs can be learned and then used during difficult times when needed. These internal exams or signs are optional, yet very helpful. For those interested in learning all the fertility signs, including the internal mucus and the cervix signs, read Natural Family Planning: The Complete Approach. The manual is in an easy-to-understand question-and-answer format.