Alpha-fetoprotein Test (AFP)

• AFP is a prenatal screening test that measures the level of AFP in the pregnant person’s blood



• AFP is a protein produced by the fetal liver and yolk sac that crosses the placenta and enters the maternal circulation
• AFP can detect neural tube defects such as spina bifida or anencephaly by measuring the level of AFP in the maternal serum (MSAFP) or in the amniotic fluid (AFAFP)
• AFP can also detect other fetal anomalies such as abdominal wall defects, renal anomalies, chromosomal abnormalities, .
• AFP is usually performed between 15 and 20 weeks of gestation
• AFP involves drawing a blood sample from the pregnant person’s arm and sending it to a laboratory for analysis
• AFP results are reported as multiples of the median (MoM), which compare the measured level of AFP to the expected level for a given gestational age
• A high level of AFP (>2.5 MoM) may indicate a neural tube defect, an abdominal wall defect, a fetal demise, or a multiple gestation
• A low level of AFP (<0.5 MoM) may indicate a chromosomal abnormality such as Down syndrome, trisomy 18, or trisomy 13
• AFP results are affected by factors such as maternal weight, diabetes mellitus, race, ethnicity, .
• AFP results are not diagnostic and require further evaluation such as ultrasound, amniocentesis, or karyotyping
• AFP has no risks or complications for the pregnant person or the fetus