When is it done:
The alpha-fetoprotein (AFP) blood test is a test that screens for possible abnormalities of a baby. A baby's liver secretes a sugar protein called alpha-fetoprotein and this protein will be evident in the mother's blood. Elevated levels of AFP may indicate defects such as spina bifida (open spine) or anencephaly (absence of the brain and part of the skull) or open abdominal (tummy) wall defects.
Low levels suggest Down's syndrome or other chromosomal defects. Should the test results not read at normal levels, it could lead to additional tests such as an amniocentesis.
The AFP test does not determine the existence of disorders; it only predicts their increased likelihood. The AFP test is often done in conjunction with an ultrasound and can be done either alone or in addition to other blood tests. The results are usually returned within a few days.