Extrapolation of maternal weight in sequential aneuploidy screening

Area of Science:

• Prenatal screening
• Maternal health
• Genetics

Background:

• Sequential screening protocols are vital for prenatal diagnosis.
• Maternal weight is a key factor in risk calculation.
• Missing second trimester weight data can complicate risk assessment.

Purpose of the Study:

• To evaluate methods for handling missing maternal weight data in sequential screening.
• To assess the impact of different weight handling strategies on risk calculation accuracy.

Main Methods:

• Retrospective analysis of 38,986 sequential screens.
• Comparison of three strategies: no weight adjustment, using first trimester weight, and using predicted second trimester weight.
• Prediction of second trimester weight using a random-effects, multi-level model.

Main Results:

• The screen positive rate for Down syndrome was 3.0% and for trisomy 18 was 0.12%.
• Strategies involving first trimester weight (0.11% switch) and predicted weight (0.06% switch) significantly reduced risk category changes compared to no adjustment (0.50%).

Conclusions:

• Using first trimester or predicted second trimester weight is a cost-effective solution for laboratories.
• These methods ensure robust risk calculations and interpretations without excessive resource use.
• Improves the reliability of sequential screening protocols when data is incomplete.