DIURNAL CHANGES IN THE CONCENTRATION OF PROGESTERONE IN THE PLASMA OF WOMEN AT 34–35 WEEKS OF GESTATION

Abstract

The concentration of progesterone has been measured in ten women at 34–35 weeks of gestation in blood samples taken at 30 or 60 min intervals during a 24 h study period. Plasma progesterone concentrations showed a distinct diurnal rhythm. Most values determined between 04.00 and 11.00 h were significantly lower than the peak concentrations measured between 13.00 and 01.00 h. The relation of these changes in plasma progesterone to those in plasma cortisol and oestrogens is discussed.