At what week of gestation should a client be tested for maternal serum alpha-fetoprotein?

Testing for maternal serum alpha-fetoprotein (MSAFP) is typically conducted between 15 and 20 weeks of gestation, with the optimal time being around 16 to 18 weeks. This test is a part of prenatal screening and helps assess the risk of certain fetal abnormalities, including neural tube defects and Down syndrome.

Week 16 is the preferred time frame because it allows for adequate fetal development to produce measurable levels of alpha-fetoprotein in the maternal serum, while also ensuring that the results can be interpreted effectively in conjunction with other prenatal screening tests. If testing is done too early, as in week 12, the alpha-fetoprotein levels may not yet be reflective of the fetus’s status. Waiting until week 20 or later may delay important decision-making regarding further diagnostic testing or interventions if abnormalities are detected. Therefore, week 16 represents the ideal compromise for accurate assessment and management during pregnancy.