Blood levels of 17-hydroxycorticosteroids in normal pregnancy.

Blood levels of 17-hydroxycorticosteroids in 124 pregnant women, in 37 women immediately after delivery, in 10 women 6 days after delivery and in 21 normal healthy women were studied. The 17-hydroxycorticosteroids were determined by the method of Nelson and Samuels. 17-hydroxycroticosteroids increased during pregnancy with a positive correlation between the level of these steroids and the duration of pregnancy. The levels increased to about 4 times the normal value during the last trimester. Immediately after delivery the levels increased to about 7 times the normal value but by the 6th day postdelivery, the levels had dropped to normal levels. The fetal cortex may contribute to the increased levels during the latter part of pregnancy but it remains to be explained why there is an increase in early pregnancy and just after delivery.