High AFP in maternal serum is a marker for?

High levels of alpha-fetoprotein (AFP) in maternal serum are primarily associated with neural tube defects (NTDs). AFP is a protein produced by the fetal liver and is usually present in the amniotic fluid. It enters the maternal bloodstream and can be measured via serum screening during pregnancy. When neural tube defects such as spina bifida or anencephaly occur, there is an increased amount of AFP that leaks into the amniotic fluid and subsequently into the maternal serum, leading to elevated levels detectable during prenatal screening.

Monitoring AFP levels is part of routine prenatal care, and significantly elevated levels typically prompt further investigation, often including detailed ultrasound and additional testing. This screening is particularly important for early detection of potential developmental issues, allowing for informed decision-making and planning for potential interventions.

While elevated AFP levels can be seen in other conditions such as multiple gestations or abdominal wall defects, it is the association with neural tube defects that is most commonly recognized in clinical practice and genetic counseling contexts.