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Evaluation of the Basal Body Temperature
Evaluation of the Basal Body Temperature An Analysis of 1012 Basal Body Temperature Recordings
Samuel L. Siegler, M.D., and Alvin M. Siegler, M.D.
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T IS GENERALLY ACCEPTED that the principle of physiologic and biologic variability holds for the reproductive process, as well as for other physiologic and biologic phenomena. The human fertile period is a variable one, changing from cycle to cycle, and each woman must be studied to understand her particular cycle. Abnormal gonadal function plays a dominant part in the problem of infertility. In the course of our study of the infertile couple, we have employed the basal body temperature in the hope that more accurate information of gonadal function could be obtained. The phenomenon of the biphasic graph during the normal menstrual cycle has been generally accepted as evidence of cyclic ovarian function and has been widely used for the interpretation of normal and abnormal ovarian activity. Uncertainty still exists, however, as to the chronologie relationship between the thermal shift and ovulation as well as the optimum time for conception according to the temperature charts. The observations and comprehensive reviews of the literature published by D. Barton, Rubenstein, Tompkins, Davis, Buxton, M. Barton, Palmer, Siegler, and others greatly facilitate the study of this subject and render unnecessary complete bibliography. The purpose of this paper is to evaluate 1012 basal body temperature graphs and to focus attention on some of the inadequacies in our present knowledge of their interpretation .. This study suggests: 1. that the basal body temperature graphs do not indicate precisely when ovulation has taken place or the quality of the ovum released;
Presented before the Brooklyn Gynecological Society, May 17, 1951. 287
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2. that the biphasic temperature curve may be an indication that ovulation had occurred in a specific cycle but is no proof thereof, unless conception occurred in that specific cycle; 3. that in this group of cases conception occurred with greater facility in women who had a "staircase" thermal shift than in those with the "rapid" rise; 4. that the length of the luteal phase is not a uniform one; 5. that the basal body temperature indicates if conception had occurred, but will not reflect the impending onset of labor or abortion, nor the implantation site of the fertilized ovum; 6. that the basal body temperature is of definite but limited value in infertility studies. MATERIAL Analyses were made of 1012 graphs submitted by 202 women, ages from 20 to 36 years, who s~emed to fall into the category of functional rather than organic infertility, including 25 cases in which the infertility appeared to be caused by seminal inadequacy. The latter group were women who were being studied in preparation for artificial insemination. Graphs influenced by illness and abnormal emotional or physical stimuli were discarded, as were those submitted by patients whose accuracy was questioned. At least three successive cycles were submitted by each patient, and one patient recorded 89 consecutive graphs. The menstrual cycles ranged from 22 to 55 days with a mean (average) of 29.4 days. METHODS OF SECURING TEMPERATURE RECORDS 1. Patients were instructed to take all temperatures at the same hour on awakening, per rectum, for a period of five minutes, read to a tenth of a degree Fahrenheit, and record immediately. 2. For comparison, temperatures were also taken orally in a number of instances, and in other instances rectal temperatures were taken both on awakening and retiring at night. 3. Variation in activity, lack of sleep, time of recording, and other factors influenced daily records and therefore temperatures taken under any such circumstances were properly labeled. 4. Biphasic and monophasic temperature graphs from the same patient as well as isolated irregularities indicate the necessity for recording the
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basal body temperature in at least three successive cycles before evaluation. Anovulatory cycles are not rare in ostensibly normal females. 5. Superimposed successively recorded graphs showed only a minor degree of coincidence in the relative number of days of low and high phases and time of thermal shift, although the basic composite graphs show characteristic patterns of a lowIhigh in individual patterns in individual patients. METHODS OF COMPUTATION OF DURATION OF PHASES 1. Estrogenic phase, or low temperature, from day 1 of the menses to the beginning of the thermal shift. 2. Thermal shift, lowIhigh, from the end of the sustained low phase to the beginning of the sustained high phase. 3. Luteal phase, or high temperature, from the beginning of the sustained elevation to the end of that cycle but not including the first day of menstruation.
OBSERVATIONS
Two hundred and two patients recorded 1012 cycles and of these 712 or 71 per cent were biphasic and 300 or 29 per cent were monophasic. The latter group included basal body temperatures recorded during 176 months
85.2% Biphasit
FIGURE
1.
Percentages of type of cycles. Arrow represents those monophasic cycles which subsequently became biphasic.
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of pregnancy. When we excluded the pregnancy graphs we noted that 766 or 85.2 per cent of the cycles were biphasic and 70 or 14.8 per cent were monophasic. In this latter group, 13 or 4.5 per cent had persistently "anovulatory" graphs (Fig. 1). The monophasic cycles observed in this series were unequally distributed. In 81 graphs, recorded by 25 patients subjected to .artificial insemination, 78 or 97.3 per cent were biphasic and 3 or 2.7 per cent were monophasic. In the "infertile" group, 755 graphs were recorded, of which 634 or 83.9 per cent were biphasic and 121 or 16.1 per cent were monophasic. Seventy or 34.6 per cent of the patients accounted for all of the monophasic graphs, as follows: 4 patients recorded less than 10 per cent of their graphs as monophasic, 22 from 11 to 25 per cent, 21 from 25 to 50 per cent, 7 from 51 to 75 per cent, and 16 from 76 to 100 per cent. These TABLE 1.
Analysis of 140 Conceptions Among 202 Women Treated for Functional Infertility
Type of graph
No. of patients
No. of pregnancies
%Pregnant
No. of graphs
Biphasic Mixed Monophasic Pregnancy graphs (in months)
132 56 14
109 28 3
82 50 21
561 236 39 176
data approximate the findings of Halbrecht who analyzed 1184 cycles in 425 sterility patients and noted that 225 or 19.5 per cent were monophasic. The incidence of the anovulatory as compared with ovulatory cycles, however, shows the widest variations. Our earlier studies of 2000 routine biopsies in 410 "infertile" women, taken from within one week of menstruation, the previous and subsequent bleeding dates being recorded, indicated that 25 cases or 6 per cent showed recurrent anovulatory cycles, closely approximating the data found in this evaluation of the basal temperature recordings with persistent monophasic charts. Bleedings were considered anovulatory if repeated premenstrual biopsies showed proliferative endometrium. Other observers report incidences of anovulatory menstruation of from 4 to 50 per cent. The incidence of pregnancy in the three basic pattern groups is tabulated in Table l. Of 132 women with biphasic curves, 109 or 82 per cent became pregnant, whereas in 56 women with associated monophasic-biphasic cycles
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28 or 50 per cent conceived. It is of interest to note that 3 women conceived in cycles interpreted by us as monophasic in character indicating that ovulation per se may not in itself call for the biphasic type of temperature graph. That ovulation does occur in such a pattern is further noted by Halbrecht who found in a number of cases in which the temperature remained at about the same level in both halves of the cycle, an endometrial biopsy indicating a secretory phase. ESTROGENIC OR LOW PHASE A more critical evaluation of the biphasic curves revealed that the average estrogenic, or low phase, was 16.5 days but varied from 5 to 40 days in length (Fig. 2). Palmer found that the preovulatory phase varied from 9 to 29 days. Our analyses are in agreement with what has been found by other investigators, in that the abnormality in length of the menstrual cycle is due
8-14 Days
15-21 Days
FIGURE
2.
Variability of low or estrogenic phase of cycle.
_mainly to the variability of the low temperature phase which is often noted in the same patient in successive cycles. Only 58.3 per cent of the low phases were 14 days or less and the remainder ranged from 15 to 40 days. Therefore, one has no way of actually predicting with any degree of accuracy when the shift in temperature will occur. With reference to the preovulatory dip discussed by Tompkins, we have found that in a number of graphs the temperature preceding the beginning
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of the rise is only slightly, if any, lower than that recorded on one or more previous days of the same cycle. Not infrequently the temperature rises after a low point, but then falls again and a day or more elapses before the temperature reaches a high level which it eventually maintains until just before menstruation. A plaUSible explanation for this phenomenon is perhaps that of Greulich who infers from his data that it may reHect a delay of the actual rupture of the follicle or a slow development of the corpus luteum. The unruptured follicle may be luteinized sufficiently to produce a temperature rise with no ovulation, although Engle did not observe any progesterone effect in the theca of human excised ovaries or follicles in his corTABLE 2.
Type of Thermal Shift in 140 Cycles in Which Conception Occurred
related studies of the time of ovulation between basal body temperature and the appearance of the ovaries. General agreement as to the proper evaluation of these observed phenomena awaits further understanding of the basic physiology of ovulation and the inHuence of the metabolism of the hormones on their biologic activity. THERMAL SHIFT A good deal of direct and indirect evidence seems to indicate that ovulation takes place at about the mid-interval in women menstruating approximately every 28 days, but there is as yet no proof that ovulation per se is directly connected with the thermal shift. According to some observers, failure of normal ovulation is reHected in the basal body temperature by a "staircase" rise in temperature, rather than the direct "abrupt" rise. In order to determine the relative fertility of these two groups, the conception cycles of the women who became pregnant in these groups were analyzed (Table 2). The criterion of an adequate thermal shift was taken as 0.4° F. and less than two days was considered an adequate rate of rise. The thermal shifts took from 1 to 11 days and the mean (average) was 3.5 days in duration. (Fig.
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3.) Only 33 per cent of the cases showed the so-called "rapid shift" of less than 2 days and the remainder were classified as a "staircase" type of shift. In 94 or 67 per cent of the 140 cases of conception a "staircase" or a slow temperature shift was recorded. In Farris' series 2 to 15 days was required for the completion of the temperature change and an average of 4.5 days was noted for the temperature rise from its lowest to its highest point.
FIGURE
3.
Span in days of the thermal shift.
The data in these analyses also seem to indicate that when a sudden rise did occur, it often did not repeat itself at the same time or to the same degree in the next cycle. In only 8 patients did conception occur in the month of the "abrupt" rise in which the previous month showed a "staircase" rise of the thermal shift. In 3 women where the basal body temperatures indicated "anovulatory" cycles, that is, characteristically monophasic, pregnancy occurred in that very cycle. Of the 25 conceptions in this series resulting from artificial insemination with donor specimens, 8 occurred from single inseminations; 1, three days before the rise in temperature; 2, two days before the rise; 1 at the low; 2 at the rise; 1 on the first day and 1 on the second day of the high phase of the graph. Farris states that pregnancy occurred in his series, from a single artificial insemination, as many as five days before or as long as two or three days after the rise in temperature. Other patients who have had typical biphasic curves, patent passageways, potent males, and propitious planned
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intercourse and inseminations have been unable to conceive. In these patients the continued use of basal body temperatures with the thermal shift as an indicator of the time of maximum fertility may, in part, be the cause of the infertility. Whether ovulation occurs before, during, or after the lowIhigh transition in temperature is still a matter of conjecture and furthermore it may vary in each patient in each cycle. Zuck's and Rubenstein's data with regard to "timed" conceptions in which they tested the relationship between temperature changes and ovulation, do not seem to be conclusive evidence as to the estimation of the exact time of fertilization, for data derived from such testimony should be tempered by one's realization of the usual unreliability of the human memory, particularly with regard to coital dates. Greulich, in a most objective manner, from gross and microscopic observations of recovered corpora lutea, suggests that the rise in temperature usually precedes the actual rupture of the follicle. The gross appearance of the ruptured area on the surface of the follicle gives an inaccurate estimate of how recently ovulation occurred. Corner is of the opinion that dating of the human corpus luteum on microscopic examination may be considered correct when the estimate of the age is based on that of the dated Rhesus monkey corpora lutea to the day on the first day or two days after ovulation; correct to the day plus or minus one day during the rest of the week; and correct to the day plus or minus two days after day 8. Buxton and Engle estimated that the mid-cycle rise of the basal body temperature may produce an error of as much as 4 days in determining ovulation from microscopic observations of excised corpora lute a and endometrial tissue and concluded that there is a considerable inconsistency in time relationship between temperature rise and luteal age. It is suggested that the preoperative elevated temperatures which were an indication of ovulation in their series may have been due to apprehension and other things having no connection with the hormonal cycle per se. Pommerenke attempted to correlate the production of cervical mucus with basal body temperature and noted that the two phenomena occurred simultaneously in only 52 per cent of the cycles studied. In 18 per cent, the maximal secretion occurred one to two days before the shift and in 30 per cent of the cycles, one or two days later. Luteinization of the Graafian follicle with no rupture can occur, and the basal body temperature in no way detects whether or not ovulation actually takes place.
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LUTEAL OR HIGH PHASE A. In the Menstrual Cycle
The basal body temperature is often used to determine the adequacy of luteal function. In contradistinction to the estrogenic phase, this phase is more constant but our analyses seem to indicate that a distinct variability does exist and that present concepts of a uniform, rather fixed postovulatory phase may no longer be tenable. In this series the luteal phase of temperature varied from 4 to 20 days with an average of 10.8 days. Only 14 per cent 15-20 Days
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8 Days 12 Days 9 Days
FIGURE
4.
Variability of the high or luteal phase.
of the biphasic cycles had a luteal phase of more than 14 days or less than 8 days and the remainder occurred between these two extremes (Fig. 4). In Halbrecht's series the high phase varied from 10 to 16 days. Jones and Buxton approximate the luteal phase as beginning from the first rise after the dip. The latter noted a distinct variability of the luteal phase in his series of 127 cases. According to his interpretation 75 per cent of the basal body temperature records were abnormal in some respects. A short luteal phase was considered to be less than 12 days in duration. Our analysis, using this criterion, would indicate that 62 per cent of the basal body temperature records of all the cases had an inadequate luteal phase. Endometrial biopsies at the time of menstruation of 22 patients showing
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biphasic graphs, the luteal phase rise in temperature being relatively low, indicated that 18 were of the proliferative and 4 of the immature progestational type. An explanation for these findings may be that under some conditions the theca cells of an unruptured follicle may become luteinized and the liberated hormones may metabolize sufficiently to produce only a temperature rise. Hartman, however, did not observe this phenomenon in 400 monkey ovaries. In other instances the titer of the ovarian hormones produced may be sufficient to evoke only some progestational effect on the endometrium in the absence of concomitant ovulation. A further explanation may be that of Moore who states that all the hormones ultimately exert an influence on the animal's physiologic processes, but the determination of the period at which the influence begins to take effect is difficult. Probably in no case does the secretion from an endometrial gland have a precipitous initial effect. A gradual development is characteristic in regard to the formation of secretions within the gland as well as in the development of sensitivity to the hormones on the part of the target organ. In such an evaluation, the local sensitivity or refractoriness of the endometrium and the thermogenic centers to the ovarian hormones should be considered. Obviously, correlated studies of the ovaries in such instances would substantiate such assumptions. In 3 cases the biphasic graph ran its course but no menstruation occurred at the end of the luteal phase concomitant with the drop in temperature, and subsequently a new biphasic cycle began. In these cases the endometrial biopsy showed mixed type of endometrium. Interpretation of these findings can only be speculative. It might be postulated that the ovarian factor was present but the factor controlling the bleeding mechanism-the spiral arteriolar system-was probably abnormal. Hence the endometrium could not respond normally to the hormone stimulation. B. In Pregnancy
When the high phase was prolonged for 20 days, a diagnOSiS of pregnancy was made with a very high degree of accuracy and in only 3 per cent of all of our patients was the luteal phase prolonged for more than 15 days. These data do not seem to indicate that there is any direct correlation between the height of the luteal phase and fertility nor that a variable high temperature in early pregnancy is a prognostic indication of abortion. Temperature recordings of 140 pregnant women who took their basal
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body temperatures for varying lengths of gestation, ranging from two months of gestation to term, were reviewed. The diagnosis of pregnancy in this group of patients was made primarily by a sustained luteal phase of over 20 days and was accurate in 100 per cent of cases. In general we noted, as have others, that the temperature gradually fell at about the fourth month from the high phase to the low phase. The modus operandi for this decrease in temperature is not quite clear but several explanations are advanced for this phenomenon. 1. A refractory state to the increased progesterone develops in which the thermogenic action is overcome (Buxton and Atkinson). 2. That the trophoblastic activity of the fetus on the decidua of the mother in the early months produces some sort of febrile reaction (Caffier). 3. That the regulation of temperature curves of gestation may depend not so much on the individual levels of estrogen and progesterone but rather upon the estrogen and progesterone ratio at critical points of gestation similar to those exhibited during the menstrual cycle (Magallon and Masters). We have followed 12 women to actual delivery by basal body temperatures and observed no indication, according to temperature records, as to when labor might actually ensue. In several instances in which abortion and miscarriage occurred, the seriousness of such threatened abortion was not reflected in the basal body temperature curve prior to or during its occurrence, nor did the basal body temperature curve reflect the presence of an unruptured ectopic pregnancy, 2 of which occurred in this group. Recent data submitted by Mauzey that pregnandiol excretion dropped during the last weeks of pregnancy and that the pregnandiol curve prior to fhe onset of labor rose sharply, throws further into the realm of speculation whether the action of the metabolites of estrogen and progesterone are truly reflected by the type of curve seen in the menstrual cycle and gestation as well as in their qualitative and quantitative determinations.
SUMMARY Variations in basal body temperature occur each cycle with a fairly characteristic pattern. The monop.rasic curve is generally anovulatory and may show oscillations of varying degree, but it fails to maintain two actual phases. The typically normal cycle however is biphasic in type, that is, the temperature is initially low and a mid-cycle thermal shift occurs to a high
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level where it remains until it once again becomes low premenstrually. The generally biphasic nature of a normal cycle reHects perhaps some hormonal change and is different in" each cycle for each patient. The interpretation is stillmore individualistic, depending upon the examiner. We have submitted the same graphs to different investigators and clinicians asking for an evaluation of the low phase, thermal shift, and the high phase, and asking when they would advise coitus or artificial insemination according to the basal body temperature graph. Many different impressions were received as to when these stages began and ended and when ovulation presumptively had occurred. Basal body temperatures furthermore provide no information as to the quality and susceptibility of the ovum to fertilization, nor are they a precise indicator of the time of ovulation, for many patients have been inseminated and coitus advised at the time indicated in the basal body temperature with no conceptions. CONCLUSIONS 1. Basal body temperature is of a definite but very limited value in infertility studies. 2. It is not an accurate indicator of the time of ovulation. 3. From the data submitted, it appears that conception occurred with a greater facility in women in our series who had a "staircase" thermal shift than in those with "rapid" rise. The cause for this phenomenon cannot be explained. 4. A distinct variability occurs in the length of the luteal phase. This variability does not seem to be a quantitative or a qualitative indicator of corpus luteum activity. 5. Basal body temperature is of proven value in the diagnosis of pregnancy in patients who maintain daily records. It is equally as accurate as the pregnancy tests commonly used and is less expensive. The cause of the temperature drop to the low phase at about the fourth month of gestation is still a subject for speculation. 6. Basal body temperature permits the evaluation of the efficacy of glandular, X-ray, and surgical therapy in gonadal dysfunction. 7. In considering physiolOgic and biologic variability with regard to fertilization, the time of ovulation and the criteria for its recognition are important factors in evaluating the merits of any particular method. Basal body
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temperature interpretations of the time of ovulation require both an imagination and a rare diagnostic acumen for an unquestionable verdict. 706 Eastern Parkway, Brooklyn 13, N. Y.
REFERENCES 1. Barton, D.: Yale J. BioI. & Med. 12:503, 1940. 2. Barton, Mary, in Sterility and Impaired Fertility. Cedric Lane-Roberts et al. (ed.2). New York, Paul B. Hoeber, 1948, pp. 229-230, 372-377. 3. Buxton, C. L.: "The short luteal phase." In Menstruation and Its Disorders (Ed., K T. Engle). Springfield, Ill., Charles C Thomas, 1948. 4. Buxton, C. L., and Atkinson, W. B.: J. Clin. EndocrinoI. 8:544, 1948. 5. Buxton, C. L., and Engle, K T.: Am. J. Obst. & Gynec. 60:539, 1950. 6. Caffier, P.: ZentralbI. f. Gynak. 53:2410, 1929. 7. Corner, G. W., Farris, K J., and Corner, G. W., Jr.: Am. J. Obst. & Gynec. 59:514, 1950. 8. Davis, M. K: J. A.M.A. 130:929,1946. 9. Davis, M. K: J. Clin. EndocrinoI. 8:550, 1948. 10. Farris, K J.: J. A.M.A. 138:560, 1948. 11. Farris, K J.: Human Fertility. White Plains, N. Y., The Author's Press, 1950. 12. Greulich, W. W., Morris, K S., and Black, M. K: Proc. Conf. Prob. Human Fertility, 1943 (Ed., K T. Engle). Menasha, Wis., Banta Publish. Co., 1943. 13. Halbrecht, I.: J. Obst. & Gynaec. Brit. Emp. 54:848, 1947. 14. Hartman, Carl: Personal communication, Jan., 1951. 15. Jones, S. S. K: J. A.M.A. 141:1123, 1949 . 16. Magallon, D. T., and Masters, W. R.: J. Clin. EndocrinoI. 1:511, 1950. 17. Mauzey, A. J.: Am. J. Obst. & Gynec. 60:626, 1950. 18. Moore, C. R.: J. Clin. EndocrinoI. 10:942, 1950. 19. Palmer, A.: Obst. and Gynec. Survey. 4-1-1949. 20. Pommerenke, W. T., and Vier giver, K: Am. J. Obst. & Gynec. 54:676, 1947. 21. Rubenstein, B. B.: Am. J. PhysioI. 119:635, 1937. 22. Siegler, S. L.: Fertility in Women. Philadelphia, J. B. Lippincott Co., 1944, pp. 194-201. 23. Tompkins, P.: J. A.M.A. 124:698, 1944. 24. Zuck, T. T.: Am. J. Obst. & Gynec. 36:998, 1938.
DISCUSSION DR. C. L. BUXTON, New York City: It has been a great pleasure to listen to Dr. Siegler's very comprehensive review of the biphasic temperature phenomenon that occurs with the menstrual cycle, and to his interesting interpretations concerning the temperature graphs submitted by the large number of patients reviewed. The various details of Dr. Siegler's paper emphasize again the fact that basal body temperature actually does not indicate precisely the moment when ovulation occurs, nor does the basal body temperature chart invariably indicate the presence or absence of ovulation itself. Like practically every other clinical indicator which all types of medical specialists have for determining physiological processes going on within the body, the basal body temperature is by no means infallible. In this connection it is a very interesting finding on Dr. Siegler's part
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that in his series more pregnancies occurred in patients with what he calls a "staircase" phenomenon of temperature rise than in patients who had the more abrupt rise which ought to indicate normal ovulation. I would like to ask Dr. Siegler if he does not consider it possible that this predominance of so-called "staircase phenomenon cases" has occurred because he has investigated a series of abnormal patients, that is, they are abnormal because they are being investigated as sterility problems. I suspect that, were we able to obtain temperature charts on a large number of patients who become pregnant with great ease, we would be likely to find that the vast majority had the sudden sharp rise which has come to be considered characteristic of normal ovulation. As another indication of the fallibility of the temperature rise as an indication of ovulation, Dr. Siegler mentions his occasional cases of what he calls "monophasic" curves, who on endometrial biopsy are found to have secretory endometrium and who, therefore, have probably ovulated. This has also occurred occasionally in our series of sterility cases, and we have also had a few patients submit a fairly normal temperature chart only to find later that their endometrium has shown no progestational reaction and they have bled from proliferative rather than secretory endometrium. When Dr. Siegler quotes me as having written somewhere that 75 per cent of menstrual cycles are abnormal when interpreted by the basal body temperature chart, I must qualify this statement to a certain extent by saying that the cycles reported were taken from 37 patients who were sterility problems and therefore were already in an abnormal group. Furthermore, among the cycles which I considered abnormal were the ones who had a slow or a "staircase" temperature rise, and therefore ones which Dr. Siegler now shows us to probably be within fairly normal range. At least they are normal in that it is possible for them to become pregnant. In the light of these findings of Dr. Siegler's and others, is it actually possible for us to put down a few statements of fact concerning the usefulness or uselessness of the. basal body temperature chart in the investigation and treatment of sterility and menstrual abnormalities? I believe that people who have studied this subject would generally agree with the following statements:
1. Normal menstruating women have a biphasic temperature reaction during their menstrual cycles characterized by a low plateau during the first half of the cycle, and a higher one during the latter half. 2. The rise in temperature occurs at about the time of ovulation, and is in the vast majority of cases about two weeks before the next expected period. 3. The temperature rise indicates that ovulation has occurred one or two days before, or will occur one or two days after, or is occurring at the moment of the temperature rise. 4. The temperature rise is caused by the presence of progesterone in the systemic circulation, or by some combination of progesterone and estrogen. It is apparently necessary for progesterone to be present, however, to enable the temperature to maintain its postovulatory level. 5. This biphasic temperature phenomenon does not occur in women previous to the menarche or after the menopause. It does not occur in oophorectomized women.
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6. This phenomenon may be artificially induced in castrate women by the appropriate combination and sequential therapy of estrogen and progesterone exogenously. 7. Abnormalities in the biphasic phenomenon are almost always indications of abnormalities in ovarian function. In this connection the fallibility of patients when taking their temperatures and recording them must constantly be kept in mind; surprisingly enough, it is frequently impossible for patients to take their temperatures accurately and at the proper time, and record them accurately. In the light of the above facts, of what value is this biphasic temperature reaction in the investigation and treatment of sterility? In the first place it tells us, except in very rare instances, whether a patient ovulates or not. In the second place it tells us approximately, but by no means absolutely, when she ovulates. In the third place it gives us a good notion as to whether or not there is anything wrong with progestational activity in the organism. All these facts can be determined, or at least partially determined, in other ways. Therefore I do not think, and I never have thought, that the basal body temperature record is an absolute essential in the diagnosis and treatment of sterility and menstrual abnormalities. It usually gives us fairly accurate, and frequently very interesting leads in diagnosis, and like every other diagnostic facility which is available to the doctor, the temperature chart must be properly evaluated if it is to be of any importance. It is a phYSical sign which represents an interesting physiologic phenomenon. It is up to us to interpret it accordingly.
Erratum
In Evaluation of the Barren Marriage (Fertility and Sterility 2: 1-14, 1951) it was stated on page 8 that Locke's solution was made up with 100 cc. of distilled water. This was, of course, a typographical error, and should read "lOOO cc."
Samuel L. Siegler, M.D., and Alvin M. Siegler, M.D.
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T IS GENERALLY ACCEPTED that the principle of physiologic and biologic variability holds for the reproductive process, as well as for other physiologic and biologic phenomena. The human fertile period is a variable one, changing from cycle to cycle, and each woman must be studied to understand her particular cycle. Abnormal gonadal function plays a dominant part in the problem of infertility. In the course of our study of the infertile couple, we have employed the basal body temperature in the hope that more accurate information of gonadal function could be obtained. The phenomenon of the biphasic graph during the normal menstrual cycle has been generally accepted as evidence of cyclic ovarian function and has been widely used for the interpretation of normal and abnormal ovarian activity. Uncertainty still exists, however, as to the chronologie relationship between the thermal shift and ovulation as well as the optimum time for conception according to the temperature charts. The observations and comprehensive reviews of the literature published by D. Barton, Rubenstein, Tompkins, Davis, Buxton, M. Barton, Palmer, Siegler, and others greatly facilitate the study of this subject and render unnecessary complete bibliography. The purpose of this paper is to evaluate 1012 basal body temperature graphs and to focus attention on some of the inadequacies in our present knowledge of their interpretation .. This study suggests: 1. that the basal body temperature graphs do not indicate precisely when ovulation has taken place or the quality of the ovum released;
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2. that the biphasic temperature curve may be an indication that ovulation had occurred in a specific cycle but is no proof thereof, unless conception occurred in that specific cycle; 3. that in this group of cases conception occurred with greater facility in women who had a "staircase" thermal shift than in those with the "rapid" rise; 4. that the length of the luteal phase is not a uniform one; 5. that the basal body temperature indicates if conception had occurred, but will not reflect the impending onset of labor or abortion, nor the implantation site of the fertilized ovum; 6. that the basal body temperature is of definite but limited value in infertility studies. MATERIAL Analyses were made of 1012 graphs submitted by 202 women, ages from 20 to 36 years, who s~emed to fall into the category of functional rather than organic infertility, including 25 cases in which the infertility appeared to be caused by seminal inadequacy. The latter group were women who were being studied in preparation for artificial insemination. Graphs influenced by illness and abnormal emotional or physical stimuli were discarded, as were those submitted by patients whose accuracy was questioned. At least three successive cycles were submitted by each patient, and one patient recorded 89 consecutive graphs. The menstrual cycles ranged from 22 to 55 days with a mean (average) of 29.4 days. METHODS OF SECURING TEMPERATURE RECORDS 1. Patients were instructed to take all temperatures at the same hour on awakening, per rectum, for a period of five minutes, read to a tenth of a degree Fahrenheit, and record immediately. 2. For comparison, temperatures were also taken orally in a number of instances, and in other instances rectal temperatures were taken both on awakening and retiring at night. 3. Variation in activity, lack of sleep, time of recording, and other factors influenced daily records and therefore temperatures taken under any such circumstances were properly labeled. 4. Biphasic and monophasic temperature graphs from the same patient as well as isolated irregularities indicate the necessity for recording the
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basal body temperature in at least three successive cycles before evaluation. Anovulatory cycles are not rare in ostensibly normal females. 5. Superimposed successively recorded graphs showed only a minor degree of coincidence in the relative number of days of low and high phases and time of thermal shift, although the basic composite graphs show characteristic patterns of a lowIhigh in individual patterns in individual patients. METHODS OF COMPUTATION OF DURATION OF PHASES 1. Estrogenic phase, or low temperature, from day 1 of the menses to the beginning of the thermal shift. 2. Thermal shift, lowIhigh, from the end of the sustained low phase to the beginning of the sustained high phase. 3. Luteal phase, or high temperature, from the beginning of the sustained elevation to the end of that cycle but not including the first day of menstruation.
OBSERVATIONS
Two hundred and two patients recorded 1012 cycles and of these 712 or 71 per cent were biphasic and 300 or 29 per cent were monophasic. The latter group included basal body temperatures recorded during 176 months
85.2% Biphasit
FIGURE
1.
Percentages of type of cycles. Arrow represents those monophasic cycles which subsequently became biphasic.
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of pregnancy. When we excluded the pregnancy graphs we noted that 766 or 85.2 per cent of the cycles were biphasic and 70 or 14.8 per cent were monophasic. In this latter group, 13 or 4.5 per cent had persistently "anovulatory" graphs (Fig. 1). The monophasic cycles observed in this series were unequally distributed. In 81 graphs, recorded by 25 patients subjected to .artificial insemination, 78 or 97.3 per cent were biphasic and 3 or 2.7 per cent were monophasic. In the "infertile" group, 755 graphs were recorded, of which 634 or 83.9 per cent were biphasic and 121 or 16.1 per cent were monophasic. Seventy or 34.6 per cent of the patients accounted for all of the monophasic graphs, as follows: 4 patients recorded less than 10 per cent of their graphs as monophasic, 22 from 11 to 25 per cent, 21 from 25 to 50 per cent, 7 from 51 to 75 per cent, and 16 from 76 to 100 per cent. These TABLE 1.
Analysis of 140 Conceptions Among 202 Women Treated for Functional Infertility
Type of graph
No. of patients
No. of pregnancies
%Pregnant
No. of graphs
Biphasic Mixed Monophasic Pregnancy graphs (in months)
132 56 14
109 28 3
82 50 21
561 236 39 176
data approximate the findings of Halbrecht who analyzed 1184 cycles in 425 sterility patients and noted that 225 or 19.5 per cent were monophasic. The incidence of the anovulatory as compared with ovulatory cycles, however, shows the widest variations. Our earlier studies of 2000 routine biopsies in 410 "infertile" women, taken from within one week of menstruation, the previous and subsequent bleeding dates being recorded, indicated that 25 cases or 6 per cent showed recurrent anovulatory cycles, closely approximating the data found in this evaluation of the basal temperature recordings with persistent monophasic charts. Bleedings were considered anovulatory if repeated premenstrual biopsies showed proliferative endometrium. Other observers report incidences of anovulatory menstruation of from 4 to 50 per cent. The incidence of pregnancy in the three basic pattern groups is tabulated in Table l. Of 132 women with biphasic curves, 109 or 82 per cent became pregnant, whereas in 56 women with associated monophasic-biphasic cycles
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28 or 50 per cent conceived. It is of interest to note that 3 women conceived in cycles interpreted by us as monophasic in character indicating that ovulation per se may not in itself call for the biphasic type of temperature graph. That ovulation does occur in such a pattern is further noted by Halbrecht who found in a number of cases in which the temperature remained at about the same level in both halves of the cycle, an endometrial biopsy indicating a secretory phase. ESTROGENIC OR LOW PHASE A more critical evaluation of the biphasic curves revealed that the average estrogenic, or low phase, was 16.5 days but varied from 5 to 40 days in length (Fig. 2). Palmer found that the preovulatory phase varied from 9 to 29 days. Our analyses are in agreement with what has been found by other investigators, in that the abnormality in length of the menstrual cycle is due
8-14 Days
15-21 Days
FIGURE
2.
Variability of low or estrogenic phase of cycle.
_mainly to the variability of the low temperature phase which is often noted in the same patient in successive cycles. Only 58.3 per cent of the low phases were 14 days or less and the remainder ranged from 15 to 40 days. Therefore, one has no way of actually predicting with any degree of accuracy when the shift in temperature will occur. With reference to the preovulatory dip discussed by Tompkins, we have found that in a number of graphs the temperature preceding the beginning
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of the rise is only slightly, if any, lower than that recorded on one or more previous days of the same cycle. Not infrequently the temperature rises after a low point, but then falls again and a day or more elapses before the temperature reaches a high level which it eventually maintains until just before menstruation. A plaUSible explanation for this phenomenon is perhaps that of Greulich who infers from his data that it may reHect a delay of the actual rupture of the follicle or a slow development of the corpus luteum. The unruptured follicle may be luteinized sufficiently to produce a temperature rise with no ovulation, although Engle did not observe any progesterone effect in the theca of human excised ovaries or follicles in his corTABLE 2.
Type of Thermal Shift in 140 Cycles in Which Conception Occurred
related studies of the time of ovulation between basal body temperature and the appearance of the ovaries. General agreement as to the proper evaluation of these observed phenomena awaits further understanding of the basic physiology of ovulation and the inHuence of the metabolism of the hormones on their biologic activity. THERMAL SHIFT A good deal of direct and indirect evidence seems to indicate that ovulation takes place at about the mid-interval in women menstruating approximately every 28 days, but there is as yet no proof that ovulation per se is directly connected with the thermal shift. According to some observers, failure of normal ovulation is reHected in the basal body temperature by a "staircase" rise in temperature, rather than the direct "abrupt" rise. In order to determine the relative fertility of these two groups, the conception cycles of the women who became pregnant in these groups were analyzed (Table 2). The criterion of an adequate thermal shift was taken as 0.4° F. and less than two days was considered an adequate rate of rise. The thermal shifts took from 1 to 11 days and the mean (average) was 3.5 days in duration. (Fig.
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3.) Only 33 per cent of the cases showed the so-called "rapid shift" of less than 2 days and the remainder were classified as a "staircase" type of shift. In 94 or 67 per cent of the 140 cases of conception a "staircase" or a slow temperature shift was recorded. In Farris' series 2 to 15 days was required for the completion of the temperature change and an average of 4.5 days was noted for the temperature rise from its lowest to its highest point.
FIGURE
3.
Span in days of the thermal shift.
The data in these analyses also seem to indicate that when a sudden rise did occur, it often did not repeat itself at the same time or to the same degree in the next cycle. In only 8 patients did conception occur in the month of the "abrupt" rise in which the previous month showed a "staircase" rise of the thermal shift. In 3 women where the basal body temperatures indicated "anovulatory" cycles, that is, characteristically monophasic, pregnancy occurred in that very cycle. Of the 25 conceptions in this series resulting from artificial insemination with donor specimens, 8 occurred from single inseminations; 1, three days before the rise in temperature; 2, two days before the rise; 1 at the low; 2 at the rise; 1 on the first day and 1 on the second day of the high phase of the graph. Farris states that pregnancy occurred in his series, from a single artificial insemination, as many as five days before or as long as two or three days after the rise in temperature. Other patients who have had typical biphasic curves, patent passageways, potent males, and propitious planned
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intercourse and inseminations have been unable to conceive. In these patients the continued use of basal body temperatures with the thermal shift as an indicator of the time of maximum fertility may, in part, be the cause of the infertility. Whether ovulation occurs before, during, or after the lowIhigh transition in temperature is still a matter of conjecture and furthermore it may vary in each patient in each cycle. Zuck's and Rubenstein's data with regard to "timed" conceptions in which they tested the relationship between temperature changes and ovulation, do not seem to be conclusive evidence as to the estimation of the exact time of fertilization, for data derived from such testimony should be tempered by one's realization of the usual unreliability of the human memory, particularly with regard to coital dates. Greulich, in a most objective manner, from gross and microscopic observations of recovered corpora lutea, suggests that the rise in temperature usually precedes the actual rupture of the follicle. The gross appearance of the ruptured area on the surface of the follicle gives an inaccurate estimate of how recently ovulation occurred. Corner is of the opinion that dating of the human corpus luteum on microscopic examination may be considered correct when the estimate of the age is based on that of the dated Rhesus monkey corpora lutea to the day on the first day or two days after ovulation; correct to the day plus or minus one day during the rest of the week; and correct to the day plus or minus two days after day 8. Buxton and Engle estimated that the mid-cycle rise of the basal body temperature may produce an error of as much as 4 days in determining ovulation from microscopic observations of excised corpora lute a and endometrial tissue and concluded that there is a considerable inconsistency in time relationship between temperature rise and luteal age. It is suggested that the preoperative elevated temperatures which were an indication of ovulation in their series may have been due to apprehension and other things having no connection with the hormonal cycle per se. Pommerenke attempted to correlate the production of cervical mucus with basal body temperature and noted that the two phenomena occurred simultaneously in only 52 per cent of the cycles studied. In 18 per cent, the maximal secretion occurred one to two days before the shift and in 30 per cent of the cycles, one or two days later. Luteinization of the Graafian follicle with no rupture can occur, and the basal body temperature in no way detects whether or not ovulation actually takes place.
r
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LUTEAL OR HIGH PHASE A. In the Menstrual Cycle
The basal body temperature is often used to determine the adequacy of luteal function. In contradistinction to the estrogenic phase, this phase is more constant but our analyses seem to indicate that a distinct variability does exist and that present concepts of a uniform, rather fixed postovulatory phase may no longer be tenable. In this series the luteal phase of temperature varied from 4 to 20 days with an average of 10.8 days. Only 14 per cent 15-20 Days
r
8 Days 12 Days 9 Days
FIGURE
4.
Variability of the high or luteal phase.
of the biphasic cycles had a luteal phase of more than 14 days or less than 8 days and the remainder occurred between these two extremes (Fig. 4). In Halbrecht's series the high phase varied from 10 to 16 days. Jones and Buxton approximate the luteal phase as beginning from the first rise after the dip. The latter noted a distinct variability of the luteal phase in his series of 127 cases. According to his interpretation 75 per cent of the basal body temperature records were abnormal in some respects. A short luteal phase was considered to be less than 12 days in duration. Our analysis, using this criterion, would indicate that 62 per cent of the basal body temperature records of all the cases had an inadequate luteal phase. Endometrial biopsies at the time of menstruation of 22 patients showing
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biphasic graphs, the luteal phase rise in temperature being relatively low, indicated that 18 were of the proliferative and 4 of the immature progestational type. An explanation for these findings may be that under some conditions the theca cells of an unruptured follicle may become luteinized and the liberated hormones may metabolize sufficiently to produce only a temperature rise. Hartman, however, did not observe this phenomenon in 400 monkey ovaries. In other instances the titer of the ovarian hormones produced may be sufficient to evoke only some progestational effect on the endometrium in the absence of concomitant ovulation. A further explanation may be that of Moore who states that all the hormones ultimately exert an influence on the animal's physiologic processes, but the determination of the period at which the influence begins to take effect is difficult. Probably in no case does the secretion from an endometrial gland have a precipitous initial effect. A gradual development is characteristic in regard to the formation of secretions within the gland as well as in the development of sensitivity to the hormones on the part of the target organ. In such an evaluation, the local sensitivity or refractoriness of the endometrium and the thermogenic centers to the ovarian hormones should be considered. Obviously, correlated studies of the ovaries in such instances would substantiate such assumptions. In 3 cases the biphasic graph ran its course but no menstruation occurred at the end of the luteal phase concomitant with the drop in temperature, and subsequently a new biphasic cycle began. In these cases the endometrial biopsy showed mixed type of endometrium. Interpretation of these findings can only be speculative. It might be postulated that the ovarian factor was present but the factor controlling the bleeding mechanism-the spiral arteriolar system-was probably abnormal. Hence the endometrium could not respond normally to the hormone stimulation. B. In Pregnancy
When the high phase was prolonged for 20 days, a diagnOSiS of pregnancy was made with a very high degree of accuracy and in only 3 per cent of all of our patients was the luteal phase prolonged for more than 15 days. These data do not seem to indicate that there is any direct correlation between the height of the luteal phase and fertility nor that a variable high temperature in early pregnancy is a prognostic indication of abortion. Temperature recordings of 140 pregnant women who took their basal
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body temperatures for varying lengths of gestation, ranging from two months of gestation to term, were reviewed. The diagnosis of pregnancy in this group of patients was made primarily by a sustained luteal phase of over 20 days and was accurate in 100 per cent of cases. In general we noted, as have others, that the temperature gradually fell at about the fourth month from the high phase to the low phase. The modus operandi for this decrease in temperature is not quite clear but several explanations are advanced for this phenomenon. 1. A refractory state to the increased progesterone develops in which the thermogenic action is overcome (Buxton and Atkinson). 2. That the trophoblastic activity of the fetus on the decidua of the mother in the early months produces some sort of febrile reaction (Caffier). 3. That the regulation of temperature curves of gestation may depend not so much on the individual levels of estrogen and progesterone but rather upon the estrogen and progesterone ratio at critical points of gestation similar to those exhibited during the menstrual cycle (Magallon and Masters). We have followed 12 women to actual delivery by basal body temperatures and observed no indication, according to temperature records, as to when labor might actually ensue. In several instances in which abortion and miscarriage occurred, the seriousness of such threatened abortion was not reflected in the basal body temperature curve prior to or during its occurrence, nor did the basal body temperature curve reflect the presence of an unruptured ectopic pregnancy, 2 of which occurred in this group. Recent data submitted by Mauzey that pregnandiol excretion dropped during the last weeks of pregnancy and that the pregnandiol curve prior to fhe onset of labor rose sharply, throws further into the realm of speculation whether the action of the metabolites of estrogen and progesterone are truly reflected by the type of curve seen in the menstrual cycle and gestation as well as in their qualitative and quantitative determinations.
SUMMARY Variations in basal body temperature occur each cycle with a fairly characteristic pattern. The monop.rasic curve is generally anovulatory and may show oscillations of varying degree, but it fails to maintain two actual phases. The typically normal cycle however is biphasic in type, that is, the temperature is initially low and a mid-cycle thermal shift occurs to a high
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level where it remains until it once again becomes low premenstrually. The generally biphasic nature of a normal cycle reHects perhaps some hormonal change and is different in" each cycle for each patient. The interpretation is stillmore individualistic, depending upon the examiner. We have submitted the same graphs to different investigators and clinicians asking for an evaluation of the low phase, thermal shift, and the high phase, and asking when they would advise coitus or artificial insemination according to the basal body temperature graph. Many different impressions were received as to when these stages began and ended and when ovulation presumptively had occurred. Basal body temperatures furthermore provide no information as to the quality and susceptibility of the ovum to fertilization, nor are they a precise indicator of the time of ovulation, for many patients have been inseminated and coitus advised at the time indicated in the basal body temperature with no conceptions. CONCLUSIONS 1. Basal body temperature is of a definite but very limited value in infertility studies. 2. It is not an accurate indicator of the time of ovulation. 3. From the data submitted, it appears that conception occurred with a greater facility in women in our series who had a "staircase" thermal shift than in those with "rapid" rise. The cause for this phenomenon cannot be explained. 4. A distinct variability occurs in the length of the luteal phase. This variability does not seem to be a quantitative or a qualitative indicator of corpus luteum activity. 5. Basal body temperature is of proven value in the diagnosis of pregnancy in patients who maintain daily records. It is equally as accurate as the pregnancy tests commonly used and is less expensive. The cause of the temperature drop to the low phase at about the fourth month of gestation is still a subject for speculation. 6. Basal body temperature permits the evaluation of the efficacy of glandular, X-ray, and surgical therapy in gonadal dysfunction. 7. In considering physiolOgic and biologic variability with regard to fertilization, the time of ovulation and the criteria for its recognition are important factors in evaluating the merits of any particular method. Basal body
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temperature interpretations of the time of ovulation require both an imagination and a rare diagnostic acumen for an unquestionable verdict. 706 Eastern Parkway, Brooklyn 13, N. Y.
REFERENCES 1. Barton, D.: Yale J. BioI. & Med. 12:503, 1940. 2. Barton, Mary, in Sterility and Impaired Fertility. Cedric Lane-Roberts et al. (ed.2). New York, Paul B. Hoeber, 1948, pp. 229-230, 372-377. 3. Buxton, C. L.: "The short luteal phase." In Menstruation and Its Disorders (Ed., K T. Engle). Springfield, Ill., Charles C Thomas, 1948. 4. Buxton, C. L., and Atkinson, W. B.: J. Clin. EndocrinoI. 8:544, 1948. 5. Buxton, C. L., and Engle, K T.: Am. J. Obst. & Gynec. 60:539, 1950. 6. Caffier, P.: ZentralbI. f. Gynak. 53:2410, 1929. 7. Corner, G. W., Farris, K J., and Corner, G. W., Jr.: Am. J. Obst. & Gynec. 59:514, 1950. 8. Davis, M. K: J. A.M.A. 130:929,1946. 9. Davis, M. K: J. Clin. EndocrinoI. 8:550, 1948. 10. Farris, K J.: J. A.M.A. 138:560, 1948. 11. Farris, K J.: Human Fertility. White Plains, N. Y., The Author's Press, 1950. 12. Greulich, W. W., Morris, K S., and Black, M. K: Proc. Conf. Prob. Human Fertility, 1943 (Ed., K T. Engle). Menasha, Wis., Banta Publish. Co., 1943. 13. Halbrecht, I.: J. Obst. & Gynaec. Brit. Emp. 54:848, 1947. 14. Hartman, Carl: Personal communication, Jan., 1951. 15. Jones, S. S. K: J. A.M.A. 141:1123, 1949 . 16. Magallon, D. T., and Masters, W. R.: J. Clin. EndocrinoI. 1:511, 1950. 17. Mauzey, A. J.: Am. J. Obst. & Gynec. 60:626, 1950. 18. Moore, C. R.: J. Clin. EndocrinoI. 10:942, 1950. 19. Palmer, A.: Obst. and Gynec. Survey. 4-1-1949. 20. Pommerenke, W. T., and Vier giver, K: Am. J. Obst. & Gynec. 54:676, 1947. 21. Rubenstein, B. B.: Am. J. PhysioI. 119:635, 1937. 22. Siegler, S. L.: Fertility in Women. Philadelphia, J. B. Lippincott Co., 1944, pp. 194-201. 23. Tompkins, P.: J. A.M.A. 124:698, 1944. 24. Zuck, T. T.: Am. J. Obst. & Gynec. 36:998, 1938.
DISCUSSION DR. C. L. BUXTON, New York City: It has been a great pleasure to listen to Dr. Siegler's very comprehensive review of the biphasic temperature phenomenon that occurs with the menstrual cycle, and to his interesting interpretations concerning the temperature graphs submitted by the large number of patients reviewed. The various details of Dr. Siegler's paper emphasize again the fact that basal body temperature actually does not indicate precisely the moment when ovulation occurs, nor does the basal body temperature chart invariably indicate the presence or absence of ovulation itself. Like practically every other clinical indicator which all types of medical specialists have for determining physiological processes going on within the body, the basal body temperature is by no means infallible. In this connection it is a very interesting finding on Dr. Siegler's part
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that in his series more pregnancies occurred in patients with what he calls a "staircase" phenomenon of temperature rise than in patients who had the more abrupt rise which ought to indicate normal ovulation. I would like to ask Dr. Siegler if he does not consider it possible that this predominance of so-called "staircase phenomenon cases" has occurred because he has investigated a series of abnormal patients, that is, they are abnormal because they are being investigated as sterility problems. I suspect that, were we able to obtain temperature charts on a large number of patients who become pregnant with great ease, we would be likely to find that the vast majority had the sudden sharp rise which has come to be considered characteristic of normal ovulation. As another indication of the fallibility of the temperature rise as an indication of ovulation, Dr. Siegler mentions his occasional cases of what he calls "monophasic" curves, who on endometrial biopsy are found to have secretory endometrium and who, therefore, have probably ovulated. This has also occurred occasionally in our series of sterility cases, and we have also had a few patients submit a fairly normal temperature chart only to find later that their endometrium has shown no progestational reaction and they have bled from proliferative rather than secretory endometrium. When Dr. Siegler quotes me as having written somewhere that 75 per cent of menstrual cycles are abnormal when interpreted by the basal body temperature chart, I must qualify this statement to a certain extent by saying that the cycles reported were taken from 37 patients who were sterility problems and therefore were already in an abnormal group. Furthermore, among the cycles which I considered abnormal were the ones who had a slow or a "staircase" temperature rise, and therefore ones which Dr. Siegler now shows us to probably be within fairly normal range. At least they are normal in that it is possible for them to become pregnant. In the light of these findings of Dr. Siegler's and others, is it actually possible for us to put down a few statements of fact concerning the usefulness or uselessness of the. basal body temperature chart in the investigation and treatment of sterility and menstrual abnormalities? I believe that people who have studied this subject would generally agree with the following statements:
1. Normal menstruating women have a biphasic temperature reaction during their menstrual cycles characterized by a low plateau during the first half of the cycle, and a higher one during the latter half. 2. The rise in temperature occurs at about the time of ovulation, and is in the vast majority of cases about two weeks before the next expected period. 3. The temperature rise indicates that ovulation has occurred one or two days before, or will occur one or two days after, or is occurring at the moment of the temperature rise. 4. The temperature rise is caused by the presence of progesterone in the systemic circulation, or by some combination of progesterone and estrogen. It is apparently necessary for progesterone to be present, however, to enable the temperature to maintain its postovulatory level. 5. This biphasic temperature phenomenon does not occur in women previous to the menarche or after the menopause. It does not occur in oophorectomized women.
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6. This phenomenon may be artificially induced in castrate women by the appropriate combination and sequential therapy of estrogen and progesterone exogenously. 7. Abnormalities in the biphasic phenomenon are almost always indications of abnormalities in ovarian function. In this connection the fallibility of patients when taking their temperatures and recording them must constantly be kept in mind; surprisingly enough, it is frequently impossible for patients to take their temperatures accurately and at the proper time, and record them accurately. In the light of the above facts, of what value is this biphasic temperature reaction in the investigation and treatment of sterility? In the first place it tells us, except in very rare instances, whether a patient ovulates or not. In the second place it tells us approximately, but by no means absolutely, when she ovulates. In the third place it gives us a good notion as to whether or not there is anything wrong with progestational activity in the organism. All these facts can be determined, or at least partially determined, in other ways. Therefore I do not think, and I never have thought, that the basal body temperature record is an absolute essential in the diagnosis and treatment of sterility and menstrual abnormalities. It usually gives us fairly accurate, and frequently very interesting leads in diagnosis, and like every other diagnostic facility which is available to the doctor, the temperature chart must be properly evaluated if it is to be of any importance. It is a phYSical sign which represents an interesting physiologic phenomenon. It is up to us to interpret it accordingly.
Erratum
In Evaluation of the Barren Marriage (Fertility and Sterility 2: 1-14, 1951) it was stated on page 8 that Locke's solution was made up with 100 cc. of distilled water. This was, of course, a typographical error, and should read "lOOO cc."