HORMONAL FACTORS INVOLVED IN THE REGULATION OF BASAL BODY TEMPERATURE DURING THE MENSTRUAL CYCLE AND PREGNANCY*

Abstract

THE biphasic aspect of the basal body temperature during the normal menstrual cycle is now a well-established fact. The temperature rise of three-fifths to one degree Fahrenheit which occurs at or about the time of ovulation is a phenomenon frequently used diagnostically and therapeutically. There are frequent variations from this typical biphasic curve, with its abrupt midcycle rise, which have been commented upon elsewhere (1), but generally speaking the rise maintains itself until the onset of the next menstrual period during which it drops to its preovulatory level. In the event that pregnancy occurs and the next menstrual period fails to appear when expected, the basal temperature does not return to its preovulatory level, but continues at or about the level maintained during the latter two weeks of the menstrual cycle. This, in itself, is a fairly accurate diagnostic sign of pregnancy. The purpose of this paper is two-fold: first, to present evidence as to the actual cause of the temperature rise during the latter half of the menstrual cycle and second, to investigate the progress of the basal body temperature throughout pregnancy.