Screening for Down’s syndrome

Major fetal abnormalities occur with a frequency of about 1-2% at birth. One such abnormality is Down’s syndrome, or mongolism, which has an incidence of about 1 in 650 births. Although the syndrome is likely to occur more often in the babies of older women, the majority of babies with Down’s syndrome (numerically) are born to younger women with no obvious risk factors, therefore some form of screening procedure is required for their detection.