Ovarian Hormones · Progesterone
Lindberg BS et al., 1974 · Acta Obstet Gynecol Scand
Plasma progesterone levels were estimated by competitive protein binding in 815 samples from healthy pregnant women with uncomplicated pregnancies. This series includes 32 patients who were followed serially throughout pregnancy. The mean level increased from 47 ng/ml in week 22 to 148 ng/ml in week 41. The spread was large. Individual patients showed very large variations between two consecutive weeks.
Diurnal variations were examined in 7 patients and short-time variations during one hour in 5 patients. Large but non-systematic variations were found in most cases. The maximal difference between values observed over a 24-hour-period was 123 ng/ml and during one hour 150 ng/ml.
Plasma progesterone levels were studied in 87 cases of toxemia of pregnancy, 6 cases of hypertension, 54 cases of Rh-immunization, 37 cases of diabetes and 5 cases of fetal growth retardation of unknown origin. The results indicate that no constant changes occur in plasma progesterone levels in these groups or in cases of impending fetal death.
As the normal limits are very wide, the intraindividual variations large, and the progesterone values in high risk pregnancies are inconclusive, plasma progesterone estimates during the latter part of pregnancy seem to be of limited value.
During human pregnancy large amounts of progesterone are produced by the placenta (1, 14). The production rate during the third trimester lies between 200 and 300 mg/day (9). Part of the progesterone produced is metabolized to pregnanediol and excreted in the urine as the 3-glucuronidate (16). The percentage of conversion to pregnanediol seems to vary with the stage of gestation and is influenced by pathological alterations in risk pregnancies (2, 5).
Large day to day variations in the urinary pregnanediol levels have been found. It is thus hardly surprising that the clinical value of serial determinations of urinary pregnanediol in late pregnancy has been limited.
Recently useful methods for the assay of progesterone in plasma have been developed and applied to physiological and clinical studies. A number of reports dealing with the prognostic value of progesterone determinations in complicated pregnancies have been published (8, 12, 17). The number of cases investigated is, however, small and the results are, in many respects, inconclusive. The aim of the present investigation was to determine the normal limits during the latter half of uncomplicated pregnancies, circadian and short-time variations, and to evaluate the prognostic value of progesterone determinations in plasma in high risk pregnancies.
Ovarian Hormones · Progesterone
Johansson ED, 1969 · Acta Endocrinol (Copenh)
Plasma levels of progesterone* were measured during normal human pregnancy by a sensitive and rapid competitive protein binding technique. During the first half of gestation 440 determinations in 321 women and in the second half of gestation, 209 determinations in 160 women were performed.
The average plasma level of progesterone in the 5th week of gestation was 24.8 ± 7.3 (s) ng/ml which is above the normal range of the luteal plateau of the menstrual cycle (10–20 ng/ml). Between the 5th and the 9th week of gestation the plasma concentration decreased significantly. From the 9th to the 32nd week of gestation the plasma level of progesterone increased from 16.7 ± 7.4 (s) to 125.2 ± 37.9 (s) ng/ml. During the last 8 weeks of gestation the plasma levels of progesterone did not show any significant rise. One woman was followed up from the day of ovulation to the 8th week of gestation. An increase in progesterone levels was observed about 10 days after ovulation. Morning samples of progesterone, which were taken before the 20th week of gestation, when the woman was still in bed, were found to be somewhat higher than levels found during the remainder of the day.
Progesterone concentrations in a few abnormal pregnancies are also reported.
Ovarian Hormones · Progesterone
Ottesen B et al., 1979 · Acta Obstet Gynecol Scand
Conflicting results have been published regarding changes in plasma progesterone during the last trimester of pregnancy. Some have demonstrated a fall in plasma progesterone before labor, and this has been taken as a possible explanation of the onset of labor. It has been suggested that the various results could be due to differences in methods for progesterone determination. In this study the progesterone levels were determined by both RIA and CPB. In 11 women the plasma progesterone, human placenta lactogen, and serum estriol were measured weekly during the last trimester of normal pregnancies and immediately after delivery. All samples were analysed radioimmunologically. In order to compare the radioimmunoassay and competitive protein binding techniques (RIA and CPB), the progesterone levels were determined by both methods. This was also done for 80 successive plasma progesterone routine samples drawn from women who were not pregnant or who were in the early stages of pregnancy. Both methods showed a significant rise in the plasma progesterone level during the last 6 weeks before spontaneous labor. However, the values obtained were lower when assayed by CPB than by RIA, presumably because of a higher specificity and a cross reaction in RIA. Serum estriol exhibited increasing values throughout pregnancy, but without a significant rise during the last few weeks. Plasma HPL settled at a constant level during the last few weeks before labor.
Ovarian Hormones · Progesterone
Tulchinsky D et al., 1975 · Am J Obstet Gynecol
The plasma concentration of progesterone (P) has been measured by radioimmunoassay in maternal peripheral vein (M.P.V.) at early pregnancy and in M.P.V. umbilical artery (U.A.) and umbilical vein (U.V.) at term pregnancy. In early preganacy marked hour-to-hour fluctuation of plasma progesterone was noted. At term pregnancy plasma P levels of U.V. were higher than those of U.A. and the umbilical venous arterial differences of plasma P did not differ between male and femal fetuses. Administration of hydrocortisone and ACTH to patients scheduled to undergo cesarean section had no effect on M.P.V., U.A., and U.V. plasma P concentration. On the basis of the differences between U.V. and U.A. plasma P concentrations and reported umbilical flow it was estimated that the secretion rate of P into the fetal circulation is approximately 23 mg. per 24 hr. and would amount to approximately 10 per cent of the reported total daily production rate of P at term pregnancy. The fraction of P which is unbound to the plasma proteins was estimeated by equilibrium dialysis at 37 degrees C. The per cent unbound P in M.P.V. plasma of pregnant patients at term was not different from that of nonpregnant patients but was 40 per cent lower than that in umbilical cord plasma (P LESS THAN 0.01), and the ratio between the concentrations of unbound P and estradiol in M.P.V. increased as pregnancy progressed. Plasma P in re-eclamptic patients who subsequently sustained intrauterine fetal death had no value in assessing placental function.
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