Before the development of the Billings Ovulation Method®, the pre-ovulatory phase of the cycle presented insoluble problems, so far as techniques of natural family planning were concerned. There was no dependable solution other than total abstinence, sometimes very prolonged abstinence, as there are a number of situations when ovulation may be suspended for a considerable period of time, even several months or perhaps a year or more. Some thought that natural methods could never provide an answer for the pre-ovulatory phase because of uncertainty about sperm survival time. The solution came from recognition of the fact that the cervical mucus not only gives warning of the approach of ovulation, but is of fundamental importance to the time of sperm survival. A fundamental concept of the Billings Ovulation Method® is that of the Basic Infertile Pattern (BIP) during the pre-ovulatory phase of the cycle. The recognition of her Basic Infertile Pattern is the key to the woman’s understanding and management of the prolonged pre-ovulatory situation.

Lengthening of a menstrual cycle is due to lengthening of the pre-ovulatory phase of the cycle. Sometimes an unusually long cycle occurs suddenly as an isolated event in a young woman. In other cases considerable irregularity may be habitual. Severe physical or emotional stress can delay ovulation and thus be responsible. Following the cessation of contraceptive medication irregularity is common, especially in those women who were irregular before they commenced to take the medication. During lactation, ovulation is usually suppressed during the production of breast milk and the result is a particular example of a very long cycle. 

With the development of sexual maturity, at the beginning of reproductive life (menarche), there is considerable variation in the interval between bleeding and in the mucus patterns; for one or two years periodic bleeding may occur without ovulation. At the time of the change of life (peri-menopause), cycle irregularity is common again; some cycles are short (early ovulation) and some cycles are long (late ovulation) and with increasing frequency intermittent bleeding occurs without any ovulation at all.

Sperm cells depend upon the presence of a particular kind of cervical mucus, in the absence of which the woman will remain infertile even though she may ovulate. In these situations, when there is no cervical response to rising oestrogens, the Basic Infertile Pattern persists throughout the cycle.

When ovulation is delayed the oestrogens may fluctuate and sometimes the level will be high enough to cause a vaginal or cervical response: the woman will notice that the Basic Infertile Pattern is interrupted by discharge or perhaps bleeding. If the bleeding is not preceded by the Peak, signifying ovulation, the cycle is still in the pre-ovulatory phase, and the Early Day Rules apply to the continuing Basic Infertile Pattern. When ovulation is delayed, two weeks of charting without sexual contact and with no bleeding will establish whether the pattern is revealing the unchanging pattern of infertility and a new Basic Infertile Pattern can be identified.

Women should be persuaded to abandon the count of days from the beginning of menstruation as an indication of when the next menstrual bleed is likely to occur (Rhythm Method calculations). The next menstruation will not come until after ovulation, and the time of ovulation cannot be predicted with certainty in this way. If it is the intention to avoid pregnancy, the Early Day Rules of the Billings Ovulation Method® must be followed until ovulation is recognized, however long this happens to be after the last menstruation. Likewise, conception cannot occur until ovulation, and therefore the expected date of delivery of a baby cannot be accurately calculated from the date of the last menstrual bleed.  Once a woman has been taught her individual pattern of reproductive physiology she becomes very familiar with it and confidently interprets its subtle variations. It is the pre-ovulatory phase of the cycle which requires her special attention to obtain this level of awareness.

When an unfamiliar situation is encountered, there is much wisdom in the husband and wife accepting a “wait-and-see” attitude, with temporary abstinence from genital contact. During the course of a long pre-ovulatory phase the Basic Infertile Pattern of dry days or unchanging discharge may be interrupted by patches of mucus. The woman will recognise this as a change from her Basic Infertile Pattern, but it will not be known at first whether it will progress to ovulation or not; the Rules have been designed to provide for this.

It is necessary to emphasize that the advice to “chart with abstinence” means the avoidance of all genital contact. This is necessary to avoid confusion resulting from the presence of seminal fluid, which is observed as a discharge following intercourse, or by the secretions of the vagina which are stimulated by the physical contact of intercourse, including interrupted intercourse and intercourse with barrier methods of contraception, such as the condom or diaphragm. The biological foundations of the Billings Ovulation Method® make it very difficult to apply the Early Day Rules and the Peak Rule correctly if sexual intercourse with barrier contraception or withdrawal is substituted for the avoidance of genital contact on those days when this is prescribed by the Rules. Additionally, if these methods are used during the fertile phase of the cycle pregnancy may result. The Rules mean what they say and the competent teacher will always make this clear. It is abstinence during the fertile phase that ensures the avoidance of pregnancy.

The woman’s attention to the cervical mucus should not be distracted by reference to other techniques such as a temperature record, which may give misleading information and always suggests that the observations are going to require continued verification. Mucus should never be taken from the cervix or vagina as this is another technique which causes confusion and errors.

Once a Basic Infertile Pattern is defined and understood in the current situation, the Early Day Rules can be applied, so that unnecessary abstinence, for example, waiting until after ovulation has occurred, will be avoided. Ovulation may be delayed for months in some circumstances. The Basic Infertile Pattern is recorded either with a plain green stamp or “I” symbol (dry days) or a plain yellow stamp or “=” symbol (unchanging discharge) as an indication that the ovary is in an inactive state, so far as the production of ovarian hormones and of ova is concerned. The cervix does not produce the oestrogenic mucus because of the low (basic) level of circulating oestrogen. When the ovary responds to stimulation by the pituitary gland there will be an observable effect on the cervical mucus, that is, a change from the Basic Infertile Pattern.

It is of paramount importance that the teacher should help the woman to understand that it is not necessary for ovulation to be identified before the couple can be sure of infertility. If the problem is that of difficulty in achieving pregnancy, it may be some time before the woman is able to recognize a Peak. A poor mucus secretion may be the cause of the problem, especially if the woman has recently ceased taking contraceptive medication or fertility is suppressed by ovarian dysfunction. If the woman is peri-menopausal she may never experience a Peak again. The Billings Ovulation Method™ is applicable in these and all other circumstances.

This article is an extract from Billings Atlas of the Ovulation Method: the mucus patterns of fertility and infertility by Evelyn L Billings, John J Billings and Maurice Catarinich, Fifth Edition 1989, pp 31-32. It has been revised by Dr E L Billings 2009.