Co-variables in first trimester maternal serum screening

Area of Science:

• Maternal-Fetal Medicine
• Prenatal Diagnostics
• Biochemistry

Background:

• First-trimester screening for Down syndrome relies on maternal serum markers.
• Accurate interpretation of these markers is crucial for effective prenatal diagnostics.
• Factors like maternal characteristics can influence marker levels, potentially affecting screening accuracy.

Purpose of the Study:

• To investigate the impact of maternal weight, smoking, gravidity, parity, and fetal gender on serum markers used in first-trimester Down syndrome screening.
• To identify key co-variables that necessitate adjustment in Down syndrome screening protocols.

Main Methods:

• Analysis of 2449 unaffected singleton pregnancies.
• Measurement of maternal serum free beta-human chorionic gonadotrophin (hCG), alpha-fetoprotein (AFP), and pregnancy-associated plasma protein-A (PAPP-A).
• Expression of marker levels as multiples of the median (MoM) and adjustment for maternal weight and other covariates.

Main Results:

• Maternal weight showed a significant negative association with all three markers (PAPP-A, free beta-hCG, AFP).
• Maternal smoking significantly reduced PAPP-A levels (median 0.81 MoM) and non-significantly reduced free beta-hCG.
• Primagravidas had significantly higher AFP levels, while female fetuses were associated with higher free beta-hCG and lower AFP levels.

Conclusions:

• Maternal weight and smoking are critical co-variables for PAPP-A in first-trimester screening.
• Gravidity, parity, and fetal gender also demonstrate influence on one or more first-trimester screening markers.
• Adjusting for these factors is essential for optimizing the accuracy of Down syndrome screening.