[Cost effectiveness analysis of prenatal screening of trisomy 21 by maternal serum markers (hCG)].

Introduction of maternal serum markers for prenatal screening of Down's syndrome leads to a redefinition of the criteria used for identifying at risk women (i.e. in France, mainly based on maternal age of 38 and over). Effectiveness and costs of prenatal screening of Down's syndrome using such maternal serum markers will vary depending on the biological cut-off values defined, at each maternal age, to identify the population of pregnant women that will be sent to amniocentesis. On the basis of the first French prospective study of the use of human chorionic gonadotropin (hCG) measurement in maternal serum as a predictor of an increased risk of Down's syndrome, this paper shows that a screening policy combining maternal age with hCG measurement is more cost-effective than screening on the basis of maternal age alone. However, final decisions about hCG cut-off values should take into account the complex ethical dilemmas involved, especially the potential consequences of "false positives" and "false negatives", of this marker.