What is Alpha-Fetoprotein?
Alpha-fetoprotein (AFP) is thought to be the fetus’s version of albumin. It is produced during the development of the fetus by the yolk sac. In the pregnant woman, AFP is produced by the liver during gestation. AFP can be measured in urine and blood. There is no proven use for the plasma protein in a pregnant woman, but there is some thought it plays a role inhibiting estradiol from passing through the placenta, but this idea has not been proven in clinical testing. Increased levels of AFP in prenatal blood test can be an indication of open neural tube defect and Down syndrome.

Normal Value Range

  • Negative Pregnancy Adult: < 15 ng/mL or < 15 µg/liter
  • Pregnancy Trimester One: 18 to 119 ng/mL or 18 to 119 µg/liter
  • Pregnancy Trimester Two: 96 to 302 ng/mL or 96 to 302 µg/liter
  • Pregnancy Trimester Three: 160 to 550 ng/mL or 160 to 550 µg/liter

Values are given as minimum and maximum results. The sample size for these results was small.

< Laboratory Values During Pregnancy