First trimester, second trimester, and integrated screening for Down's syndrome in China

Area of Science:

• Prenatal diagnostics
• Genetics
• Maternal-fetal medicine

Background:

• Down's syndrome screening is crucial for prenatal care.
• Evaluating different screening timings and methods is essential for optimizing detection rates.
• Previous studies have shown varying effectiveness of different screening protocols.

Purpose of the Study:

• To compare the diagnostic effectiveness of first trimester, second trimester, and integrated screening for Down's syndrome.
• To assess detection and false-positive rates for each screening method.
• To identify the most effective screening strategy for Down's syndrome in a Chinese population.

Main Methods:

• A prospective study involving 11,966 pregnant women in two Chinese centers.
• First trimester screening included serum markers (free beta-human chorionic gonadotrophin, pregnancy-associated protein-A) and nuchal translucency.
• Second trimester screening included serum markers (beta-human chorionic gonadotrophin, alpha fetoprotein).
• Integrated screening combined results from both trimesters.
• Risk assessment was performed using specialized computer software.

Main Results:

• The incidence of Down's syndrome was 0.2% (23/11,966).
• At a 5% false-positive rate, detection rates were 73.9% (first trimester), 69.6% (second trimester), and 82.6% (integrated).
• At a 3% false-positive rate, detection rates were 65.2% (first trimester), 56.5% (second trimester), and 73.9% (integrated).

Conclusions:

• Integrated screening was the most effective method for Down's syndrome screening in this Chinese population.
• The findings support the use of integrated screening for improved detection rates.
• This study highlights the importance of population-specific screening strategy evaluation.