Unconjugated Estriol (E3)

Unconjugated estriol (uE3) is a form of oestrogen (hormone) produced by the fetus (unborn baby) through metabolism. Estriol levels are used to determine birth defects and chromosomal variations in babies. Estriol is ejected from the placenta (an organ acting as the protective covering for the fetus) into the mother’s blood, and measured as unconjugated uE3.