What is the rate of incidence for chromosomal disorders?

Some chromosomal disorders are more common than others. Scientists estimate that approximately one in every 200 babies is born with a chromosomal abnormality of one kind or another. Chromosomal abnormalities are also thought to be responsible for at least 50 percent of miscarriages that happen in the first trimester. Down syndrome is currently the most commonly occurring type of chromosomal disorder among live births.