ESTRIOL- Estriol is one of three estrogen hormones. Estriol levels rise throughout pregnancy, helping to keep your uterus and unborn baby healthy. The levels are at their highest right before childbirth. They help prepare your body for labor and delivery. used to monitor high-risk pregnancies and screen for problems with the fetus The estriol blood test is also known as an Estriol Serum Test, E3, Serum, Pregnancy, Estriol and Unconjugated Estriol The estriol blood test evaluates fetal distress and placental function in the management of patients facing complications such as fetal growth retardation, pre-eclampsia, Rh immunization, diabetes, choriocarcinoma and hydatidiform mole.