Catholic Medical Quarterly

The Journal of the Catholic Medical Association (UK)

Building knowledge. Building faith. Protecting the vulnerable.

Catholic Medical Quarterly Volume 62(4) November 2012

Natural fertility regulation

Dr Helen Davies

“For man cannot attain that true happiness for which he yearns with all the strength of his spirit, unless he keeps the laws which the Most High God has engraved in his very nature.”

Photo 1Pope Paul VI in his 1968 Encyclical appealed to men of science to establish a secure basis for the natural regulation of births (HV P.24). He also appealed to doctors and nurses to regard it as an essential part of their skill to make themselves fully proficient in this field: “For then, when married couples consult them, they will be able to give them proper advice and show them a way that is lawful. This, indeed, they have every right to expect.” (HV P.27)

Photo 2Doctors John and Evelyn Billings of Melbourne, Australia, answered this call by their work on the Ovulation Method which bears their name [1].This gave couples a safe, simple and effective means of achieving or avoiding a pregnancy. The efficacy of the authentic method has been verified in trials undertaken by the World Health Organisation[2] in the late 1970s, and more recently in a Chinese study[3]. Both showed the importance of correct understanding of the method and its rules and access to accurate information and assistance. This has been greatly helped by resources now available online, but there will always be a place for a well-organised service of trained and accredited teachers, particularly where couples are experiencing difficulties.

The Billings Ovulation Method

The breakthrough for Dr John Billings was the recognition of the association between changes in cervical mucus and fertility. By asking women to record the pattern of vulval discharge throughout the length of their cycles, Billings realised that it could be recognised when a woman was fertile, regardless of cycle length. His wife, Dr Evelyn Billings, helped with the recognition of the pattern of pre-ovulatory infertility in the early 1960s. This was a pattern of either dryness or unchanging discharge and it helped eradicate the uncertainties associated with irregular cycles or delayed ovulation. Further research confirmed the validity of the Billings Ovulation Method and the rules have remained unchanged since that time[4,5].

The Hormonal Basis of the Method

Changes in cervical mucus are controlled by changing production of oestradiol and progesterone during the ovarian cycle. The woman’s observations of her cervical mucus are in effect self-bioassays for these hormones.

The ovulatory cycle can be divided into two phases: from the beginning of menstruation until the day of optimal fertility in that cycle (‘the peak’), and from the peak until the beginning of the next menstruation (the luteal phase).

The interval between ovulation and the next menstruation is 11-16 days in a fertile cycle, but the length of the pre-ovulatory phase will vary and maybe extended, resulting in long cycles, for example in breast-feeding, perimenopausal women or women suffering ovarian dysfunction such as polycystic ovary syndrome.

During the time of fertility, the cervix produces mucus that is conducive to sperm selection, transport and survival, progressing over a variable number of days to a slippery sensation at the vulva. The last day on which this slippery mucus is present, whether in large or minimal quantities, is the peak. Genital contact over the fertile phase has the potential to result in pregnancy. Women using the Billings Ovulation Method are taught to be aware of the sensation at the vulva and any visible discharge as they go about their daily activities and to record this information each evening. The woman’s record gives her information about the current state of her fertility, regardless of cycle length or reproductive life stage and the likely day of ovulation.

This information is valuable for all women, whether they are wishing to avoid pregnancy or conceive. It is also of particular benefit in enabling women to monitor their reproductive health, as they will be alerted to any abnormal discharge and seek early medical management.

The Billings Ovulation Method is incompatible with any barrier methods of contraception, including withdrawal, as valid observations are compromised. Internal examinations or touching of mucus do not form part of the Billings Ovulation Method, as these can give inaccurate information.

Cycle Variants

For most of her reproductive life a woman will experience fertile ovulatory cycles. However, all women will experience infertile variants of the ovulatory cycle, particularly during breast-feeding, approach of menarche and menopause, periods of stress and during and after hormonal contraception.

The hormone patterns and therefore the symptoms in these infertile cycles differ from those of the fertile ovulatory cycle. Recognising these variants is particularly important for achieving pregnancy. The ovulatory cycle has been extensively studied, but the other variants have been largely overlooked, as they are not predictable. Large numbers of cycles needed to be studied so that the variants could be documented and their mechanism, frequency and impact on the mucus symptoms and fertility determined. Professor James B. Brown’s work on the normal variants of ovarian activity from menarche to menopause ‘the continuum’, has provided information on all phases and variants of reproductive life[5].

Using the Method

To-day, with the availability of the internet, it is possible for women to inform themselves about their fertility in a way unknown to their predecessors. The problem is that they may become overloaded with information, some of which may be misleading. The beauty of this method is its simplicity, and it is important that it is simply but accurately presented to them so they will have confidence in their ability to make it work for them.

The woman’s chart record reveals whether the cycle is a fertile ovulatory cycle or one of the variants. Fertility and infertility is understood on a day by day basis, regardless of the length of the cycle and fertility is managed by following the four rules of the method. Although with the authentic online teaching resources now available it may be possible for couples to teach themselves the method, the service of an accredited teacher is recommended. This may be through either face-to-face, telephone or internet counselling, especially where there are difficulties with comprehension, record-keeping or interpretation; or during changing circumstances such as following childbirth or approaching the menopause.

Too often the sexual self-control required to practice abstinence for short periods of time during the cycle, when the intention is to avoid a pregnancy, is seen as an insuperable obstacle. Couples who know the method do not report this and their relief at being able to use a simple, effective natural method to manage their fertility, which is without health risks, promotes communication between them and is in accord with the Church’s teaching, becomes increasingly apparent. This important knowledge will also be handed on in the family.

What can doctors and nurses do?

At recent seminars for doctors and other health professionals held in Australia on the Billings Ovulation Method and infertility [6], pre-session questionnaires completed by attendees revealed a lack of current knowledge on the science and signs of fertility. This, coupled with the fact that a five-year study conducted there on the use of the method to achieve a pregnancy revealed that only 18% of couples wishing to conceive had prior knowledge of their signs of fertility, indicates the importance of accurate information on the significance of mucus and cervical health for fertility.

The online resources and (the official sites) are excellent for updating, as well as providing material to download. We know there needs to be a see-change in attitudes to fertility education to counteract an endemic contraceptive mentality in the UK. Now the resources are available to enable us to inform ourselves and answer the call made 44 years ago.

Dr Helen Davies, retired GP and former Master of the Sussex Branch,
The Billings Ovulation Method Centre,
c/o 4 Southgate Drive,
West Sussex
RH10 6RP.

To contact the Sussex branch please email

With acknowledgment to ‘Australian Doctor Education’ 19 December 2008. The full article may be downloaded from the above websites.


  1. Billings E.L. et al. Symptoms and hormonal changes accompanying ovulation, Lancet 1: 282-4, 1972.
  2. World Health Organisation multicentre trial, Fertility and Sterility 1981; 36:152-58, 36:591-98.
  3. Qian S.Z. et al Evaluation of the effectiveness of a Natural Fertility Regulation Programme in China. Centre for Study and Research in the Natural Regulation of Fertility, Universita Cattolica del Sacro Cuore, Rome 8, September 2000.
  4. Odeblad E. Physical properties of cervical mucus ‘Advances in Experimental Medicine and Biology 1977; 89: 217-25. (See also ‘Scientific Basis of the Billings Ovulation Method)
  5. Brown J.B. Cycle Variants:
  6. Ovulation Method Research and Reference Centre of Australia Ltd. 2A/303 Burwood Highway, East Burwood , Victoria 3151, Australia.