Alpha-fetoprotein in maternal serum and/or amniotic fluid is increased in all except

In Down syndrome, the AFP is decreased in the mother's blood, presumably because the yolk sac and fetus are smaller than usual. Estriol is a hormone produced by the placenta, using ingredients made by the fetal liver and adrenal gland. Estriol is decreased in the Down syndrome pregnancy Ref Robbins 9/e pg 170