[Amniotic AFP concentration in pregnancies with numerical chromosome aberrations]

Area of Science:

• Obstetrics and Gynecology
• Prenatal Diagnostics
• Biochemistry

Context:

• Amniotic fluid alpha-fetoprotein (AFP) levels naturally decrease during the second trimester of pregnancy.
• Accurate gestational dating is crucial for interpreting AFP levels.
• Previous studies suggest a correlation between low amniotic fluid AFP and chromosomal abnormalities.

Purpose:

• To investigate amniotic fluid alpha-fetoprotein (AFP) levels in normal pregnancies and compare them to pregnancies with trisomic states.
• To assess the diagnostic potential of AFP in identifying numerical chromosomal aberrations.

Summary:

• A study measured amniotic fluid AFP in 360 normal pregnancies (15-23 weeks gestation), establishing gestational age-specific means and SDs.
• In 25 pregnancies with trisomic states (23 trisomy 21, 2 trisomy 18), 19 showed AFP levels below the control mean.
• While most trisomic cases had AFP levels within 1 SD below the mean, some were above or at the mean, indicating a trend but not definitive diagnostic value.

Impact:

• These findings support the observation of lower amniotic fluid AFP in pregnancies with numerical chromosomal aberrations.
• The study highlights the need for further investigation to determine the clinical utility of AFP in prenatal screening for trisomies.
• Current data do not support making clinical decisions based solely on amniotic fluid AFP levels.