<P> Estriol can be measured in maternal blood or urine and can be used as a marker of fetal health and well - being . If levels of unconjugated estriol ( uE3 or free estriol ) are abnormally low in a pregnant woman , this may indicate chromosomal or congenital anomalies like Down syndrome or Edward 's syndrome . It is included as part of the triple test and quadruple test for antenatal screening for fetal anomalies . </P>
decreased estriol levels in pregnancy are associated with
chromosomal or congenital anomalies like Down syndrome or Edward 's syndrome