Prognostic significance of unexplained elevated amniotic fluid alpha-fetoprotein

Area of Science:

• Obstetrics and Gynecology
• Maternal-Fetal Medicine
• Prenatal Screening

Background:

• Alpha-fetoprotein (AFP) is a protein produced by the fetus.
• Elevated levels of AFP in maternal serum (MSAFP) or amniotic fluid (AF AFP) can indicate potential pregnancy complications.
• Unexplained elevations require further investigation into their prognostic value.

Purpose of the Study:

• To compare the predictive capabilities of unexplained elevated amniotic fluid alpha-fetoprotein (AF AFP ≥ 2.0 multiples of the median [MoM]) and unexplained elevated maternal serum alpha-fetoprotein (MSAFP ≥ 2.5 MoM) for pregnancy outcomes.
• To assess the association of these unexplained AFP elevations with specific late pregnancy complications.

Main Methods:

• Analysis of a database of 5743 women undergoing second-trimester genetic amniocentesis (October 1988–August 1994).
• Exclusion of cases with identifiable causes for elevated AFP (e.g., fetal malformations, multiple gestation).
• Calculation of relative risks (RR) for pregnancy complications associated with unexplained elevated MSAFP and AF AFP.

Main Results:

• Elevated MSAFP (with any AF AFP) was linked to fetal growth restriction (RR 2.5), stillbirth (RR 3.5), preeclampsia (RR 2.8), and preterm delivery (RR 2.8).
• Elevated AF AFP (with any MSAFP) was associated with preeclampsia (RR 4.4) and preterm delivery (RR 1.7).
• Unexplained elevated AF AFP with normal MSAFP showed a significant association with preeclampsia (RR 4.6).

Conclusions:

• Maternal serum alpha-fetoprotein is a more comprehensive predictor of late pregnancy complications compared to AF AFP.
• Unexplained elevations in amniotic fluid alpha-fetoprotein are particularly predictive of preeclampsia.
• These findings aid in risk stratification and management of pregnancies with unexplained elevated AFP levels.