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

33. The Sympto-Thermal Methods

This title refers to family planning methods that are based on the sympto-thermal test, that is, on the study of the woman's morning temperature and on signs and symptoms at the time of ovulation that serve to delineate the fertile period as well as the infertile periods of the menstrual cycle.

The Sympto-Thermal Test


The temperature of the human body is influenced by the organism's activity and by the time of day. Moreover, in the woman, it is influenced by progesterone, the postovulatory ovarian hormone. In order to bring out this latter influence, the temperature is taken daily under comparable conditions, that is, upon awakening at about the same time, using the same route (rectal, vaginal, or oral). Changes in schedule or sleep, strong emotions, infections, and medication are noted on the relevant dates in case the temperature should be affected. If the thermometer and the graph have a broad scale, the temperature will be easier to read and interpret.

If the temperature is taken every morning under comparable and normal conditions, the curve will reveal a first level that is rather low following menstruation, then a short rising segment called shift, and finally a higher premenstrual plateau. It is recognized that the higher or upper temperature plateau is a sign of progesterone activity. One deduces then that ovulation occurred during the preceding days. The temperature, therefore, is used to obtain a retrospective confirmation of ovulation; it does not indicate the day of ovulation, nor does it predict its approach.

Signs and Symptoms

Cervical Mucus at the Vulva

There are many details on observing and interpreting this symptom. In short, the woman is invited to denote each day as: 1) day of bleeding; 2) day without mucus; 3) day with transitional or "less-fertile" mucus; or 4) day of "maximum-fertility" mucus. When a menstrual period ends, whether there have been mucus-free days or not, any manifestation of mucus should be considered the result of estrogen activity, a sign of possible fertility, and a forerunner of ovulation sooner or later. Once the mucus has acquired and lost its maximum-fertility characteristics (mainly a sensation of lubrification), the woman enters and remains in the infertile phase until the next menstruation (or exceptionally, until a new mucus episode).

The sympto-thermal methods ask that the woman note her mucus observations either using her own words (NOFZIGER, 1979), or in the form of a chart (FALLACE, 1976), or using a code (PHARAND-LAPOINTE, 1980; LEBLANC, 1977; ROETZER, 1978; KIPPLEY, 1979-7 GUY, 1979).

Changes in the Cervix

In 1962 KEEFE showed that daily self-palpation of the cervix reveals changes corresponding to the phases of the cycle. In the phase following menstruation, the cervix rises more and more and is soft, open, straight; mucus flows from it. These changes are slow and gradual; they show fertility. They quickly reverse, within two or three days, indicating infertility until the end of the cycle. Initially some will be reluctant to make this examination. There is no doubt, however, that it is very useful, once the learning phase has passed.

Various Symptoms

Abdominal pain, bleeding, or breast sensitivity occurs in some women between the beginning of the mucus and the confirmation of the upper-temperature plateau. None of these signs reveal the day of ovulation, but they do show that it is close. Other women notice periodic changes in mood, sexual desire, skin, eyes, appetite, headaches, allergies, or other cycle-related problems.

Sympto-Thermal Interpretation

The total lack of mucus after menstruation is a sign of infertility for the experienced and careful woman.

The appearance of any mucus reveals the beginning of the fertile phase, culminating at the time of wetness/lubrication sensation. If the woman examines her cervix, she will find that it is high, soft, open, and straight. The temperature is still low, and abdominal pain or bloody discharge may occur.

Soon lubrification at the vulva will disappear; the mucus dries up while the temperature is rising and settling at a higher level. If the woman examines her cervix, she will find it is low, closed, firm, and dry. This all confirms the onset of the infertile phase, which will last until the return of menstruation some ten or twelve days later. This is the normal sequence of events in cycles.

There are situations, however, where estrogenic surges are not always followed by ovulation. Thus, there may be mucus episodes with or without the cervix rising, opening, and becoming soft; these will appear and disappear repeatedly during very long cycles, at the time of premenopause or in the postpartum phase, eventually alternating with nonmenstrual bleedings. The fact that the temperature stays at a low level indicates that these were not ovulatory episodes and that the reappearance of mucus should be watched for.

The Sympto-Thermal Methods

The sympto-thermal method of family planning is one in which the knowledge of symptoms and temperature guides the planning of the couple's intercourse, either to help them conceive or to prevent conception.

The Sympto-Thermal Method to Facilitate Conception

Chances of conceiving are best when the mucus has maximum lubrification and fluidity. If this mucus is ovulatory, a temperature shift will soon confirm it. One can conclude that conception has occurred if the temperature stays high for at least 20 days. The couple may increase their chances of conceiving by abstaining for a few days before impregnating intercourse.

The Sympto-Thermal Method to Avoid Conception

When a couple are not ready to welcome a child, they may abstain from intercourse during the fertile phase of the cycle. The sympto-thermal chart enables them to recognize the two infertile phases where infertile intercourse is possible. There are variations of detail around the world, but the essential points are held in common.

The Early Infertile Period

At the beginning of the cycle, a certain amount of time is required for the follicle and the ovum to develop before ovulation is possible. There is an infertile phase if the bleeding is really a menstruation, i.e., if ovulation occurred in the preceding cycle. The length of this infertile phase depends on the earliness of the next ovulation and on sperm survival for this particular couple.

From the very first sign of mucus, this infertile phase is over, practically speaking. Many groups add a mathematical rule that may terminate infertility at an earlier date, either a set number of days, or a calculation related to the shortest cycle.

The Postovulatory or Premenstrual Infertile Period

As regards the temperature component for the beginning of premenstrual infertility, there is general agreement that a minimum of three consecutive days of high temperature under normal conditions is required. There are variations in the way these high temperatures are set out: coverline (PHARAND-LAPOINTE, 1980; McCARTHY, 1977); temperature mean (VOLLMAN, 1977); or minimum upper shift (MARSHALL, 1978; KIPPLEY, 1979; NOFZIGER, 1979).

The symptom component for the beginning of premenstrual infertility refers mainly to the mucus, blood-spotting, or changes in the cervix. The mucus needs to dry up before hyperthermia is confirmed (PHARAND-LAPOINTE, 1980; ROETZER, 1978; MARSHALL, 1978; McCARTHY, 1977; KIPPLEY, 1979).

Effectiveness of the  Sympto-Thermal Methods

The effectiveness of the sympto-thermal methods depends first and foremost on the precision of the sympto-thermal test. There should. be regular observations through plotting, use of a thermometer and a chart, and teaching that is competent and progressive. Moreover, the couple should be able to consult with a teacher or counselor if they have a problem or a question, to prevent their making a mistake or becoming discouraged so that intercourse occurs at the fertile time even though they do not wish a pregnancy.

Effectiveness depends also on how the couple adapt to modifying their intercourse in terms of their objective (facilitate or prevent conception). The spouses' psychosexual adjustment will influence the effectiveness of the method; there is a strong chance they will tend to break the rules if they have not arrived together at their decision, or if they deny their problems.

Statistically it is very difficult to measure the effectiveness of natural methods as methods of conception avoidance. A multitude of subtle attitudes and behaviors have to be fitted into right concepts, whereas the assumption with natural methods is that of being open to the child. However, Table 1 shows the results of statistical studies on the effectiveness of the sympto-thermal method, calculated according to the classic Pearl technique (rate of unplanned pregnancies per 100 woman years).

In RICE (1777), couples who did not wish to have children (birth limitation) had better results than those wishing only to space births; this difference shows the effect of motivation. JOHNSTON (1978) differentiated, for users of the infertile period at the beginning of the cycle, between those who stopped on a set day determined by a modified Ogino calculation and those who stopped at the onset of mucus.

Sympto-Thermal Method Acceptability

The attention and care necessary to observe and make charts require an effort, but this effort can be compensated for by the fact that the method is effective and harmless. Moreover, it is very valuable for a woman to learn that she can detect and interpret changes in her body that formerly escaped her notice, and to understand what is happening if her cycle length is more irregular than usual.

Some people prefer the sympto-thermal methods, where they have to observe many cyclic signs; others choose natural methods based on a single parameter: temperature alone or mucus alone. In a multiparameter method there is more to teach, more to observe, and more to chart: this may be viewed either as a burden or as the benefit of having more areas of awareness to grasp the changes from one phase to another. In those rare cases of non-correlation among the various signs, the discrepancy may be viewed either as a source of confusion or as a warning that extra care is needed.

Psychosexual adjustment to periodic abstinence will be influenced by the length of possibly fertile periods, previous experience in family planning, the stage of marital adjustment, and the teacher's attitudes toward natural methods and toward couples. Finally, it will depend on the couple's ability to feel and express love, tenderness, and caring without coitus as well as through coitus. Periodic abstinence calls for the couple's communication because it implies repeated joint decisions. That is why it is important to encourage the participation of the man from the very beginning.

by Suzanne Parenteau-Carreau, M.D.

  1. Fallace, C. and J., 1976. Family Planning Guide. Smithtown, New York. The Natural Family Planning Association of Long Island.
  2. Guy, F. and M., 1979. Les Methodes d'Auto-observation. Grenoble. Institut de Recherche sur l'Enfant et le Couple.
  3. Johnston, J.A.; Roberts, D.B.; and Spencer, R.B., 1978. NFP Services and Methods in Australia: A Survey Evaluation. International Review of Natural Family Planning 2:143-154, 203-224, 328-353, and 3:20-53.
  4. Keefe, E.F., 1962. Self Observation of the Cervix to Distinguish Days of Possible Fertility. Bull. Sloane Hosp. for Women 8:129.
  5. Kippley, J. and S., 1979. The Art of Natural Family Planning. Cincinnati, Ohio. The Couple to Couple League.
  6. Leblanc and Harel, 1977, L'Action Familiale. Ile Maurice.
  7. Marshall, J., 1978. Natural Family Planning. London. Catholic Marriage Advisory Council.
  8. McCarthy, J.J.; Martin, M.C.; and Gildenhorn, M., 1977. The Sympto-Thermal Method. Washington, D.C., The Human Life Foundation of America and the Natural Family Planning Federation of America.
  9. Nofziger, M., 1979. A Cooperative Method of Natural Birth Control, 3d edition, Summertown, Tennessee, The Book Publishing Co.
  10. Pharand-Lapointe, M.; Kavanagh-Jazrawy, F.; Plante-Charron, C.; Parenteau- Carreau, S.; and Doyle, R., 1980. Planning your Family, the S. T. Way. Ottawa, Serena-Canada.
  11. Rice, J., and Lanctot, C.A., 1978. Results of a Recent Study of the Sympto-Thermal Method of Natural Family Planning. Linacre Quarterly 45:388.
  12. Rice, F.J.; Lanctot, C.A.; and Garcia-Devesa, 1977. The Effectiveness of the Sympto-Thermal Method of Natural Family Planning. Communication at First International Congress of IFFLP in Cali, Columbia, June 1977.
  13. Roetzer, J., 1978. The Sympto-Thermal Method: Ten Years of Change. The Linacre Quarterly 45:358.
  14. Thyma, P., 1978. The Double-Check-Method of Natural Family Planning. South Deerfield, Mass., Marriage Life Information.
  15. Vollman, R.F., 1977. The Menstrual Cycle. Philadelphia /London/ Toronto. Saunders.

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