Natural Family Planning: Nature's Way - God's Way

34. The Ovulation Method

The Ovulation Method is an individual method of fertility regulation in which days of infertility, possible fertility and maximum fertility are defined by self-observation of the cervical mucus pattern. These observations include the feelings produced at the vulva by the absence or presence of mucus and its physical characteristics, and the appearance of any mucus present in sufficient quantity to be seen. The technique involves the interpretation of symptoms with which the healthy, fertile woman is already familiar, and which she observes in the course of her normal activities; internal examination of the vagina is advised against.

There have been many references in the gynaecological literature to the importance of the cervical factor in human fertility. In 1855 Smith pointed out that conception is most likely to occur at that time in the menstrual cycle when the mucus 2 content of the cervix is "in its most fluid condition." In 1868 Sims described what is now called the Sims-Heuhner post-coital test for spermatozoa and emphasized that the test is most likely to show healthy, motile spermatozoa when "the cervical mucus becomes clear and translucent, and about the consistence of the white of egg." A lively interest in the cyclical changes in activity of the cervix in humans and various animals developed from 1940 onwards, when it came to be recognized that close to ovulation the cervical mucus exhibits a fern-like crystallization pattern, exhibits the formation of channels, has an increased content of glucose, sodium chloride and water and a decreased viscosity and cell content. It gradually came to be realized that infertility could result from a deficiency of the normal secretion and that the normal responsiveness of the cells of the cervical crypts to high circulating levels of oestrogen diminishes about the time of menopause.

Our studies began in the 1950's when almost all emphasis had been applied to laboratory studies of mucus aspirated from the cervix at different stages of the menstrual cycle, with only occasional reference to the occurrence of a mucus symptom, a truly remarkable situation.

The instruction is begun by inviting the woman to acknowledge that at some time between her menstrual periods she notices a vaginal loss of another kind. It is then explained that this "mucus" is an indication of the fertile time within the cycle. It is requested that she keep a daily record for a month during which time physical sexual activity and genital arousal are avoided. One is careful to avoid detailed description of an average mucus pattern, because there are individual variations. It is pointed out that the feelings evident at the vulva are more important than visual observation, and a few key words are suggested, such as "dry", "slippery", "sticky", "opaque" and "stringy". The record is made at the end of the day's activities, using a colour and a brief written description, or in the case of illiterate women merely the colour or a symbol.

More detailed instruction is given after this first month, when from her own record the woman is taught two fundamental concepts, that of the Basic infertile Pattern of mucus and that of the Peak symptom. The Basic Infertile Pattern is the reflection of ovarian inactivity, so far as follicular development is concerned, and exists in the pre-ovulatory phase of the cycle, corresponding with a low circulating level of oestrogens. Ordinarily the "dry days" constitute the Basic Infertile Pattern. In other cases the woman may experience continuous mucus, when the Basic Infertile Pattern is that mucus which does not alter in any of its characteristics day after day.

The Peak symptom results from the hormonal events which occur at the time of ovulation. The high levels of oestrogen produce a slippery, lubricative mucus which alters abruptly as the progesterone level rises at ovulation, so that the mucus becomes sticky and opaque, or ceases altogether.

Our scientific studies undertaken in Melbourne in collaboration with J.B. Brown and H.G. Burger3 have shown that ovulation occurs in a close time-relationship to the Peak symptom, usually immediately afterwards. Allowing time for ovulation to occur and the ovum to die, we can define post-ovulatory infertility from the beginning of the 4th day past the Peak symptom of the mucus -the Peak Rule. The hormonal verification of the definition of the fertile phase by reference to the cervical mucus pattern has been abundantly confirmed. 4,1,6,1 It has also been demonstrated that the woman's observations accurately reflect what is happening at the cervix.8

During the pre-ovulatory phase of the cycle, the days of the Basic Infertile Pattern are infertile. The rules for the avoidance of pregnancy (Early Day Rules) are simple to understand. There is avoidance of coitus during menstruation, in case the mucus warning of an early ovulation is obscured. Coitus is confined to the end of the day, so that the Basic Infertile Pattern has been identified. Coitus is avoided on successive days lest the seminal fluid and vaginal transudates following coitus obscure the commencement of the fertile phase. Any change from the Basic Infertile Pattern, that is, from dry days to mucus, or from mucus to a different kind of mucus, or the appearance of bleeding, are an indication for abstinence, allowing sufficient time after the return of the Basic Infertile Pattern for the woman to be sure of what is happening. In an average cycle, once there is a change from the Basic Infertile Pattern, the woman proceeds to ovulation, after which the Peak Rule is applied. There is no need for coitus to be confined to the end of the day in the post-ovulatory phase of the cycle.

The cervical mucus is not merely an indicator of the time of ovulation, it actually determines the presence of fertility, it is the fertility factor. Conception requires a good ovum, a good sperm cell and a satisfactory secretion of a particular kind of cervical mucus in the absence of which coitus remains infertile. The secretion of two kinds of mucus is stimulated by a high level of oestrogens, as Odeblad9 has shown, one forming strings and channels (Es mucus) which preserves and nourishes the sperm cells and promotes their migration, and another type which can be seen as small opaque lumps (El mucus) which appears to act as a filter whereby abnormal spermatozoa are prevented from reaching the uterine cavity. With a rise in the level of circulating progesterone a dense, sticky mucus (G mucus) is formed, and provides a complete barrier to sperm migration. The cervical mucus acts therefore as a biological valve, and determines the time for which sperm cells may survive, with the ability to fertilize the ovum, within the female genital tract.

Experience in many differing cultures and social conditions has demonstrated that even illiterate women living in poverty can understand the Ovulation Method, and this understanding is not prevented by the presence of abnormal vaginal discharges. Competent teaching is essential and it is important that the teacher concentrate on the essential simplicity of the observations. It has been our constant experience both in Australia and in other countries that attempts to teach the Ovulation Method are always unsuccessful if the teachers are also employed in offering a variety of contraceptive techniques. Additionally, there is to be noted that the biological features of the Ovulation Method exclude the concurrent use of barrier methods of contraception. The biological principles of the Ovulation Method make it incompatible also with cervical palpation. Once there has been a change from the Basic infertile Pattern, as an indication that follicular development has commenced, the woman must observe the changing characteristics of the mucus from day to day unti1 after ovulation, without the confusion created by genital arousal, internal examination or physical sexual activity.

Knowledge of the natural manifestations of her phases of fertility and infertility is knowledge which every woman should be given. It promotes the development of self-respect, recognition of the wonders of the human reproductive physiology and a deeper respect for life. Our own programed have expanded to include this teaching of fertility and infertility awareness within the schools.

In communicating the fundamental principles on which the rules of the Ovulation Method are based, the teachers make it clear that the husband and wife are completely free in their exercise of the option to apply the rules for the achievement of pregnancy or the rules for the avoidance of pregnancy.

Many people have used the Ovulation Method in an effort to determine the sex of the child before conception, with variable success. It is suggested that the Y-chromosome sperm cell is shorter lived but more motile than the X-chromosome sperm cell; according to this theory, an act of coitus on the day of the Peak symptom is more likely to produce a boy child, whereas if there is coitus a day or two before the expected time of the Peak symptom, and then abstinence until the time of post-ovulatory infertility the child is more likely to be a girl.

Current research in Melbourne and other parts of the world is directed to the production of a "do-it-yourself kit" to define the fertile phase by testing an overnight specimen of urine for its oestrogen and progesterone (Pregnanediol) content. it should not be assumed that such a kit would be a new "method" but rather a teaching-aid to help women to learn the Ovulation Method well, particularly those women who lack confidence in their own observations or perhaps have a pathological condition disturbing the normal mucus pattern.

By defining the fertile phase from its beginning, the Ovulation Method brings the husband and wife into confrontation with their fertility, and this has been repeatedly observed to promote sentiments of respect for human life. By learning to identify the Peak symptom, which may be absent in many cycles, the method can help many apparently infertile couples to have children. By teaching the woman to recognize infertility it provides a natural technique for the confident management of fertility regulation during breast-feeding and that permanent infertility which occurs at menopause. The husband and wife can be assured that if they have a serious need to avoid pregnancy, observance of the rules for the avoidance of pregnancy will give them a security that is not surpassed by any contraceptive technique,10,11 that they have avoided the ill-effects which complicate contraception and that they remain free to employ the method for the achievement of pregnancy at any time in the future.

by Evelyn L. Billings and John J. Billings

Dr. Lyn Billings graduated in Medicine from the University of Melbourne (1942), and subsequently took the Diploma of Child Health in London. She is Senior Demonstrator in Histology and Embryology in the Department of Anatomy of the University of Melbourne. She is a mother of nine children and is Assistant Physician at the Family Planning Clinic in the Department of Community Medicine at St. Vincent's Hospital, Melbourne.


  1. Smith, W.T. The Pathology and Treatment of Leukorrhoea, Churchill,
  2. London,1855.
  3. Sims, J.M. Brit. Med. J., 1868. 2:465,492.
  4. Billings, E.L. et alii. Lancet. 1972, 1,282.
  5. Flynn, A.M. and Lynch, S.S. Brit. J. Obstet. Gynaec., 1976, 83,656.
  6. Casey, J.H. Human Love and Human Life. Published by Polding Press, Melbourne 1978, 68.
  7. Hilgers, T.W. et alii. Obstet. Gynec., 1978. 52,5,575.
  8. Cortesi, S. Primo Corso Nazionale sul Metodo della Ovulazione Billings, Universita Cattolica del Sacro Cuore, Roma, 10-15 Dicembre, 1978.
  9. Hilgers, T.W. and Prebil, Ann M. Obstet. Gynec. 1979. 53,1,12.
  10. Odeblad, E. Cont. Gynec. Obstetr. 1978, 4:132.
  11. Weissman, C. et alii. Lancet. 1972, 2:813.
  12. A Prospective Multicentre Trial of the Ovulation Method of Natural Family Planning. World Health Organization Task Force on the Determination of the Fertile Period: Special Programme of Research, Development and Research Training in Human Reproduction. (To be published).
  13. Dr. John Billings graduated In Medicine from the University of Melbourne in 1941. He is a Fellow of the Royal College of Physicians of London and a Fellow of the Royal Australasian College of Physicians. He is Head of the Department of Neurology at St. Vincent's Hospital, Melbourne, Dean of the Clinical School and Associate Dean (Clinical) in the Faculty of Medicine of the University of Melbourne, Physician to the Royal Victorian Eye and Ear Hospital and Consultant Neurologist to the Cancer Institute. He is President of the World Organization of the Ovulation Method (Billings).

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