The study was to assess importance of maternal age in finding out foetus have chromosome abnormalities (Down's syndrome and Edwards syndrome). The results showed that, 6.45 percent babies with Down syndrome were born with women younger than 20 while Edwards syndrome rate was 5.56 percent, in which false positive rates are 0.14 percent and 0.2 percent respectively. In the group of women or = 35 years of age the rate of babies with Down and syndromes were to about 32.26 percent and 44.44 percent respectively while false positive rates are 23.14 percent and 23.08 percent respectively. Approximately 22.58 percent of babies with Down syndrome and 27.78 percent of babies with Edwards syndrome were found in the group of women or = 40 years of age, in which false positive rates were 4.97 percent and 5.06 percent respectively. Based on the "cut-off' of Prisca sofwave, high risk of Down syndrome due to maternal age was or = 1/250, our study showed 29.03 percent of babies have Down syndrome and false positive rate was 14.02 percent. In conclusion, the "cut-off' for screening of foetus with Down and Edwards syndrome due to maternal age was or = 40 years of age, in. which false positive rate for both of those syndromes was 5 percent. About 29.03 percent of babies were found to have Down syndrome based on.Prisca sofwave for high risk, and false positive rate was 14.02 percent.