Plasma levels of unconjugated estetrol and estriol and of total estriol in normal human pregnancy.

The course of normal pregnancy in 54 patients was monitored by weekly assays of Unconjugated Estriol (E3U), Total Estriol (E3T) and Unconjugated Estetrol (E4U). These subjects were divided into two groups: one of those patients who delivered a fetus with a weight above the 50th percentile and the other of those who delivered a fetus with a weight below the 50th percentile. No significant difference was found between these two groups and it is not therefore possible to have information regarding the weight of the fetus, starting from the weekly values of these hormones. Analogous variations of the three hormones were found as pregnancy progresses. However, the rate of increase for E4U was higher than for E3T and E3U.