Down Syndrome Screening: Normal Range for Alpha-Fetoprotein (AFP)

Hospitals generally recommend that pregnant women undergo Down syndrome screening to assess whether the fetus has Down syndrome. So, what is the normal reference range for alpha-fetoprotein (AFP) in Down syndrome screening?

Normal Reference Range for Alpha-Fetoprotein (AFP) in Down Syndrome Screening

In Down syndrome screening results, the normal range for AFP is 0.7–2.5 multiples of the median (MoM). Also known as AFP, alpha-fetoprotein is a glycoprotein present in fetal blood during embryonic development, primarily synthesized by fetal hepatocytes and the yolk sac. In clinical medicine, AFP is mainly used as a tumor marker for hepatocellular carcinoma or as an indicator for assessing fetal risk of Down syndrome. Consequently, increasing attention is being paid to the normal AFP reference range.

AFP levels in adult serum are normally extremely low. However, elevated AFP levels may result from numerous causes. In individuals with liver abnormalities, common causes of elevated AFP include hepatocellular carcinoma, chronic hepatitis B, chronic hepatitis C, cirrhosis, and extensive hepatocyte necrosis. In pregnant women, elevated AFP is most commonly associated with fetal neural tube defects, which cause excessive leakage of AFP from the fetus into maternal circulation—suggesting a possible congenital anomaly in the fetus.

Down syndrome screening is only a risk-assessment tool. Even if the test result indicates high or borderline risk, it does not definitively confirm fetal abnormality. We hope this information is helpful to you. Wishing you a happy life and good health!