Down's Syndrome Screening in the First Trimester with Additional Serum Markers: Indian Parameters

Area of Science:

• Maternal-Fetal Medicine
• Prenatal Diagnostics
• Biochemical Screening

Background:

• Down's syndrome screening in India requires region-specific algorithms.
• First-trimester screening offers early detection opportunities.

Purpose of the Study:

• To develop and validate a Down's syndrome risk calculation algorithm for the Indian population.
• To assess the performance of first-trimester maternal serum markers, alone and with nuchal translucency (NT).

Main Methods:

• Maternal serum samples from 411 unaffected pregnancies were analyzed for PAPP-A, free β-hCG, placental growth factor, and α-fetoprotein.
• Equations were derived to normalize marker levels, and Gaussian model parameters were established.
• Model performance was predicted using Indian population data for maternal age and NT screening.

Main Results:

• A serum-only protocol predicted an 80% detection rate for Down's syndrome with a 5% false-positive rate.
• Including NT ultrasound with serum markers improved detection rates to 95% (5% FPR) and 90% (1.4% FPR).

Conclusions:

• First-trimester screening for Down's syndrome using four serum markers is feasible in India.
• Combined NT and serum marker screening significantly enhances performance.
• This approach facilitates early detection and potential screening for other conditions like preeclampsia.