As indicated in the August 11 post of Dr. Edward F. Keefe’s COVERLINE article on the internal observations of cervical mucus, his patients taught him about changes in the cervix itself, changes that had not been previously reported in the medical literature. He first reported on this in 1962 in the Bulletin of the Sloane Hospital for Women. Fifteen years later he reported it in the International Review of Natural Family Planning, Vol.1, Number 1, Spring 1977. It is interesting both in its detail and in the responses he gives to questions about its effectiveness when used in systematic NFP.
As Dr. Keefe indicates in this article, squeamishness hinders some women from ever making the exam, and he addresses that issue. He never advocates a cervix-only system for purposes of avoiding pregnancy. In NFPI we teach the observation of the cervix as a supplement to the mucus and temperature signs. Experienced women have told us that that the cervix sign is sometimes the best sign for them about their fertility or infertility, especially in extended breastfeeding amenorrhea or during premenopause.
If you would like to read his 1977 report, see www.naturalfamilyplanningandmore.com/Cephalad_Shift_of_the_Cervix_Uteri.pdf.