2Richard K. E., Thomas L.C. Life Expectancy of Persons with Down syndrome. American Journal on Mental Retardation. 1991, 95(6):603-612.
3United Nations Development Program. Human development report.2OO3.
4Waitzman NJ, Romano PS, Schemer RM. Economic Costs of Birth Defects and Cerebral Palsy-United States 1992. MMWR, 1995, 44(37) : 694-699.
5Haddow J E, Palomaki G E, Knight G J et al. Screening ofmaternal serum for fetal Down' s syndrome in the first trimester, N Engl J Med,1998, 338 (5): 955
6Muller F, Dreux S , Oury J F et al. Down syndrome maternal serum marker screening after 18 weeks' gestation. Prenat Diagn, 2002, 22(11): 1001
7Benn P A, Fang M, Egan J F et al. Incorporation of inhibin - A in second_ trimester screening for Down syndrome. Obstet Gynecol, 2003,101 (3): 451
8wald NJ, Cuckle HS, Densem JW. Maternal serum screening for Down' s syndrome in early pregnancy [ J]. Br Med J, 1988,297:883 -88.
9Haddow JE, Palomaki GE, Knight GJ, et al. prenatal screening for Down's syndrome with use of maternal serum markers [ J]. N Engl J Med, 1992,327:588 - 593.