Normal alpha-fetoprotein test results are less than 40 micrograms per liter of blood in men and non-pregnant women, according to Healthline and WebMD. Expectant mothers typically take the test between the 14th and 22nd weeks of pregnancy to help screen for birth defects.
Significantly higher AFP levels may indicate a neural tube defect in the developing baby, or they could be due to an inaccurate dating of the pregnancy. Unusually low levels could indicate a chromosomal abnormality in the fetus, such as Down or Edwards syndrome, explains Healthline. Abnormally high results among men and non-pregnant women may indicate the presence of certain cancers or liver diseases.