UE3 Normal Reference Range

uE3 is a highly pregnancy-specific marker that is rarely detected in non-pregnant individuals or males. It is primarily synthesized by the fetal-placental unit. What then is the reference range for normal uE3 levels?

Reference Range for Normal uE3 Levels

UE3, or unconjugated estriol, is an estrogen produced by the placenta during pregnancy. The normal reference range is 0.5–2.0, although slight variations may occur depending on the testing reagents used by different hospitals. It is recommended to consult an obstetrician or gynecologist to interpret test results and determine whether amniocentesis is needed to assess the fetus for Down syndrome. Down syndrome screening primarily measures maternal serum levels of alpha-fetoprotein (AFP), human chorionic gonadotropin (HCG), along with maternal age, menstrual history, and gestational age at the time of blood collection, to calculate the risk coefficient for Down syndrome, thereby detecting approximately 80% of cases.

The concentration of uE3 in fetal serum increases progressively with gestational age and is approximately five times higher than that in the mother. Maternal serum uE3 levels begin to exceed non-pregnant levels between weeks 7 and 9 of gestation and continue to rise steadily, peaking just before term. On average, maternal serum uE3 levels in pregnancies affected by Down syndrome are 29% lower than those in normal pregnancies. In addition, uE3 levels in amniotic fluid from Down syndrome pregnancies are about 50% lower compared to normal pregnancies.

The optimal time for Down syndrome screening is between 16 and 18 weeks of pregnancy, when the results are most accurate. Pregnant women are advised to attend regular prenatal check-ups on schedule. We hope this information is helpful. Wishing you a pleasant life and good health!