Current software used for assessment of the risk of Down's syndrome may give misleading risk estimates if applied to other abnormalities. Often the abnormality is reflected in maternal serum α-fetoprotein and human chorionic gonadotrophin levels and is then translated into a low risk for Down's syndrome that may not be recognized as significantly atypical of normality. We regard this as a serious deficiency in the current Down's syndrome risk reporting algorithm, and suggest a modification that allows the problem to be overcome.
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