Maternal serum screening for Down's syndrome on population basis

Area of Science:

• Prenatal diagnostics
• Maternal serum screening
• Genetics

Background:

• Public acceptance of prenatal diagnostics in Finland facilitated a population-based trial.
• Introduction of screening for Down's syndrome using maternal serum markers and age.

Purpose of the Study:

• To evaluate the effectiveness and uptake of population-based prenatal screening for Down's syndrome.
• To assess the detection rates and false positive rates of the screening method.

Main Methods:

• Offered serum screening to 17,200 pregnant women in Helsinki over 2.5 years.
• Continued screening for advanced maternal age (≥37 years).
• Utilized alpha-fetoprotein, human chorionic gonadotrophin, and unconjugated estriol as markers.

Main Results:

• Serum screening uptake was 84%.
• Initial false positive rate was 5.7%, reduced to 4.1% after ultrasound.
• Detected 56% of Down's syndrome cases (10/18); sensitivity 56% (95% CI 31-79%).
• Identified other chromosomal abnormalities and placental mosaicisms.

Conclusions:

• Maternal serum screening was well-received by pregnant women.
• The 56% detection rate is comparable to previous studies.
• Pre-screening ultrasound effectively reduces false positives due to incorrect gestational age.