[Are there any changes in Down Syndrome prevalence in France following the implementation of the measurement of nuchal translucency and maternal serum screening?].

OBJECTIVE

To evaluate the impact of prenatal screening for Down Syndrome in France in relation to the important changes in the French prenatal screening policy during the years 1996-1997: measurement of nuchal translucency and maternal serum screening, for all women.

PATIENTS AND METHOD

Data are those published from three congenital anomalies registries implanted in Centre-Est, Paris and Bas-Rhin areas, from 1990 to 2001.

RESULTS

The livebirth prevalence of Down Syndrome decreased from 1/950 in 1990 to 1/1500 in 2000-2001. This decrease was observed from 1994 onwards but has proved stronger since 1996, in spite of the observed increase in the total prevalence partly explained by changes in the maternal age distribution. Extrapolated to all births in France, the calculated annual number of Down Syndrome births would decrease from 800-900 in 1990 to 500-600 in 2001. Consequently, the proportion of induced terminations following prenatal diagnosis increased from 38.6% in 1990 to 75.5% in 2001. In addition, the mean gestational age of the induced terminations is decreasing.

CONCLUSION

It seems reasonable to assume that the observed trends followed the changes in the French national policy for prenatal screening: a mass screening for all women, whatever the maternal age.