Kuroki Y, Yamamoto Y, Matsui I, Kurita T
Clin Genet. 1977 Jul;12(1):43-6. doi: 10.1111/j.1399-0004.1977.tb00899.x.
The mean maternal age and the percentage age distribution of 2,650 mothers of children with Down syndrome were calculated for 1950-1973, from hospital records. Mean maternal age had dropped both for controls (28.55 leads to 27.37) and Down syndrome (31.26 leads to 29.59). The observed maternal age distributions were very similar to those expected in corresponding periods, from the age specific incidences of Collmann & Stoller (1962). It is conceivable that the fall in maternal age in Down syndrome in recent years has resulted from the general trend to decreasing maternal age. There has been no change in the age-specific incidences of Down syndrome. The incidence of Down syndrome seems to be falling in Japan.
根据医院记录，计算了1950年至1973年期间2650名唐氏综合征患儿母亲的平均年龄及年龄分布百分比。对照组母亲的平均年龄有所下降（从28.55降至27.37），唐氏综合征患儿母亲的平均年龄也有所下降（从31.26降至29.59）。根据科尔曼和斯托勒（1962年）的年龄别发病率，观察到的母亲年龄分布与相应时期预期的分布非常相似。可以想象，近年来唐氏综合征患儿母亲年龄的下降是由于母亲年龄普遍下降的趋势所致。唐氏综合征的年龄别发病率没有变化。在日本，唐氏综合征的发病率似乎在下降。
