Forster D P
J Ment Defic Res. 1977 Dec;21(4):263-72. doi: 10.1111/j.1365-2788.1977.tb01589.x.
The numbers of Down's syndrome live births in the area covered by the Sheffield Regional Hospital Board (Trent Regional Health Authority) were estimated using age specific incidence data from a recent detailed Swedish study. The estimated number and proportion of Down's syndrome live births, which could have been detected by prenatal screening of elderly mothers at high risk, fell substantially in recent years. In the maternal age group forty to forty-four the estimated number of Down's syndrome livebirths decreased from thirty-three (24.6 per cent) in 1963 to thirteen (15.7 per cent) in 1973. Over the same period there was a fall in estimated numbers in the thirty-five to thirty-nine age group from twenty-seven (20.2 per cent) to twelve (14.5 per cent). This trend has been due predominantly to a rapid decline in the fertility rates of women aged thirty-five and over. However, projections based on the best available evidence suggest that about 11.4 per cent to 13.8 per cent of all Down's livebirths up to 1991 could be detected by screening all pregnancies in the forty to forty-four age group. A further 11.7 per cent to 14.4 per cent of Down's livebirths could be detected by screening pregnancies in the thirty-five to thirty-nine age group.
利用瑞典近期一项详细研究中的年龄特异性发病率数据，估算了谢菲尔德地区医院委员会（特伦特地区卫生局）所覆盖区域内唐氏综合征活产儿的数量。近年来，通过对高危高龄母亲进行产前筛查本可检测出的唐氏综合征活产儿数量及比例大幅下降。在40至44岁的产妇年龄组中，唐氏综合征活产儿的估算数量从1963年的33例（24.6%）降至1973年的13例（15.7%）。在同一时期，35至39岁年龄组的估算数量从27例（20.2%）降至12例（14.5%）。这一趋势主要归因于35岁及以上女性生育率的迅速下降。然而，基于现有最佳证据的预测表明，到1991年，通过对40至44岁年龄组的所有孕妇进行筛查，约11.4%至13.8%的唐氏综合征活产儿可被检测出来。通过对35至39岁年龄组的孕妇进行筛查，还可检测出另外11.7%至14.4%的唐氏综合征活产儿。
