Contribution of estriol to total urinary estrogens during pregnancy.

Estriol accounts for an average of 74% of the principal Kober-positive steroids in the urine of 13 women during uncomplicated pregnancies. This proportion is independent of the stage of pregnancy, from 20 weeks until term. The average ratio of estriol to ring-D a#{149}ketols (mainly 16ahydroxyestrone and 16-ketoestradiol-17) is about 5:1 over the same period. In 17 pregnant women with diabetes, urinary estriol averaged 63% of the “total steroids” during a similar period, and the average ratio of estriol to ring.D a-ketols was 3:1. The quantitative importance of these ketolic steroids may introduce a problem in deciding whether to measure estriol or “total estrogens” when evaluating fetal viability in complicated pregnancies.