[Correlated interrelationships between the concentrations of chorionic gonadotropin, progesterone and estriol in normal pregnancy].

A study was made of 151 healthy pregnant women at periods of from 4 to 41 weeks of pregnancy. There was revealed no correlation between the level of excretion of the CG and estriol, and also of the CG and pregnandiol from the 7th to the 41st weeks of pregnancy; consequently CG played no role in the regulation of steroidogenesis in the placenta. Between the levels of CH and progesterone in the blood there existed a significant positive association from the 4th to the 7th week of pregnancy; this correlation disappeared from the 8th week. Consequently, the CG retained its steroidogenic action on the corpus luteum of pregnancy. The activity of the corpus luteum in respect to progesterone production decreased considerably as soon as the 7th week of pregnancy.