Abstract
To determine circadian rhythm of steroid levels in normal pregnant women, the following study was undertaken. Concentrations of cortisol (F), pregnenolone-sulfate (P5-S), DHA, and DHA-S, which are considered to be secreted from adrenal glands, were measured by GC-MS in 9 normal pregnant women at 3 hour intervals through 24 hours. Except for DHA-S, a similar circadian rhythm tendency was observed for each steroid in the first second and third trimesters. The concentrations of F and DHA peaked at 6: 00 and the circadian rhythms of both steroids were similar, but P5-S reached a maximum level at 9: 00, which was different from F and DHA. DHA-S levels, however, did not fluctuate with a definite circadian rhythm. ACTH was given to normal pregnant women at 12 and 30 weeks of gestation. A significant increment of F and DHA values was observed after administration of ACTH. Although, there was no apparent change of DHA-S in response to ACTH stimulation, low response was observed in P5-S. These results suggest that the adrenocortical steroids measured each has its own circadian rhythm. The secretion patterns of F and DHA from the adrenal gland were similar but different from those of P5-S and DHA-S. Circadian rhythm of steroid concentrations in maternal plasma during pregnancy were demonstrated.
