[Investigation of the incidence of aberration in various indication for prenatal cytogenetic analysis].

In order to evaluate the role of prenatal cytogenetic analysis for the management of pregnant women, we studied the incidence of chromosomal aberration in 1,258 cases. In 502 cases with advanced maternal age (at least 35 years older), 12 (2.4%) cases of chromosome aberration were detected. The incidence of chromosomal aberration in the cases with women who had a previous child with chromosome aberration, women who had given birth to a congenital malformation child, and women who had ultrasonographic abnormalities were 3.0% (8/271), 0% (0/103) and 11.7% (36/307), respectively. Of cases with advanced maternal age, the incidence of chromosome aberration is 0% (0/21) at age 35, 0% (0/22) at age 36, 19% (1/52) at age 37, 2.2% (2/92) at age 38, 10% (1/102) at age 39, 1.3% (1/75) at age 40, 5.3% (3/56) at age 41, 6.9% (3/43) at age 42, 4.4% (1/23) at age 43 and 6.7% (1/15) at age 44. These results indicate that the incidence of chromosome aberration increases with maternal age. On the basis of these data, we recommend medical practice to offer prenatal diagnosis to all women who will be 37 or older. In the cases of fetal anomaly, they were diagnosed by ultrasonographic examination, the high incidence of chromosome aberration was detected in comparison with another group. Therefore, the prenatal cytogenetical analysis may also be performed in these cases.