Despite the expansion of prenatal screening programs, including both first and second trimester screening, we still have 98.3% of cases diagnosed postnatally, which reflects clearly the gap between the increased awareness of mental retardation and the preventive screening concept. In our study advanced maternal age was the most common reason for referral for prenatal diagnosis. In NDSCR, the reasons for prenatal referral have changed. In the early days of the NDSCR, maternal age was the major reason. But now most of the cases referred because of high risk maternal serum screening or specific ultrasound scans for nuchal fold or other ultrasound signs (3).

Prenatal detection rate of 1.7% versus 50% in developed countries makes it essential to reinforce the concept of preventive genetics in our population and to initiate a national policy targeting both health professionals and general publics to offer prenatal genetic screening for all pregnant ladies and prenatal diagnosis for screen positive cases. This needs an integrated system including diagnostic facilities, trained personnel and professional staff.