[Maternal serum AFP determination in the 2d trimester: a suitable screening method for detection of fetuses with Down's syndrome in young females?].

The frequency distributions of maternal serum alpha-fetoprotein levels in pregnancies with fetal Down syndrome (n = 84) and in unaffected pregnancies (n = 9982) were fitted to extreme value distributions. The risk of an individual woman having a pregnancy associated with Down's syndrome was estimated depending on age and serum AFP level (MOM). A risk of Down's syndrome greater than 1:384 corresponding to the risk of a greater than or equal to 35-year-old woman was chosen to the lowest risk indicating referral for amniocentesis. The retrospective analysis of our data showed an age depending sensitivity of the maternal serum AFP screening. Only five of twenty-one cases in younger women (less than 35-year-old) but all of the thirteen cases in older women (38-40 years old) could have been detected based on low AFP levels. By calculating the sensitivity of the AFP Screening it seems to be impossible to reduce clearly the risk of Down's syndrome in young women.