First-trimester screening for down syndrome with serum sampling at different gestational ages: the effect on...

Area of Science:

• Maternal-Fetal Medicine
• Prenatal Diagnostics
• Genetics

Background:

• First-trimester screening is crucial for detecting Down syndrome (DS).
• Evaluating screening performance across different gestational weeks is essential for optimizing diagnostic accuracy.

Purpose of the Study:

• To assess the performance of first-trimester Down syndrome screening using serum sampling at various gestational weeks.
• To identify optimal timing for serum sampling to maximize detection rates and minimize false positives.

Main Methods:

• Analysis of 35,431 singleton pregnancies from 2005-2011, including 145 DS cases.
• Screening performance evaluation based on serum sampling between 9 + 0 and 13 + 6 weeks of gestation.
• Stratification of results by maternal age groups.

Main Results:

• No significant differences in Down syndrome detection rates were observed across different gestational weeks.
• The false-positive rate (FPR) was comparable at 9 and 10 weeks but significantly increased from 11 weeks onwards.
• Increased FPR from week 11 was more pronounced in women aged 36 years and older.

Conclusions:

• Early serum sampling (before 11 weeks) is associated with higher screening performance for Down syndrome.
• Gestational timing of serum sampling significantly impacts the false-positive rate, especially in older maternal age groups.
• Optimizing the timing of serum sampling can improve the efficiency of first-trimester Down syndrome screening.