An alpha-fetoprotein (AFP) blood test checks the level of AFP in a pregnantwoman's blood. AFP is a substance made in the liver of an unborn baby (fetus). The amount of AFP in the blood of a pregnant woman can help see whether the baby may have such problems as spina bifida and anencephaly. An AFP test can also be done as part of a screening test to find other chromosomal problems, such as Down syndrome (trisomy 21) or Edwards syndrome (trisomy 18). An AFP test can help find an omphalocele, a congenital problem in which some of the baby's intestines stick out through the belly wall. Normally, low levels of AFP can be found in the blood of a pregnant woman. No AFP (or only a very low level) is generally found in the blood of healthy men or healthy, nonpregnant women.