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There have been concerns about the effects of increases in maternal age since the 1980s on the prevalence of Down’s syndrome. This study examined changes in the distribution of maternal age in England and Wales from 1938 to 2010. The live birth prevalence of Down’s syndrome in the absence of screening and subsequent termination was estimated using the numbers of babies born in England and Wales according to maternal age and the maternal age-related risk of a birth with Down’s syndrome. The proportion of women age 35 years or older at the time of giving birth reached a peak of 20% in 1945, declined to 5.5% in 1977 and rose to 20% in 2007. In the absence of screening and subsequent termination, the estimated live birth prevalence of Down’s syndrome would have mirrored these changes (2.3 per 1000 births in 1945, 1.2 per 1000 in 1976 and 2.2 per 1000 in 2007). The observed live birth …