Information provided by the screen

The Counsyl Prelude™ Prenatal Screen detects whether a pregnancy has an increased chance for the most common chromosome conditions.

Categories of chromosome conditions

Microdeletion and sex chromosome screening are optional.


A trisomy occurs when the cells of the body contain an extra chromosome. This can lead to health issues including birth defects and intellectual disability.

Sex chromosomes

The sex chromosomes determine whether the baby will be male (XY) or female (XX). Sometimes there may be too many or too few sex chromosomes, resulting in potential health issues.


A microdeletion occurs when a tiny piece of a chromosome is missing, or deleted. This deletion can result in birth defects or intellectual disability.