5Wald N J, Kennard A,Hackshaw A, et al. Antenatal acreening for Down's syndrome. J Med Sreen, 1997,4: 181.
6Morikawa M, et al. Embryo loss pattern is predominant in miscarria- ges with normal chromosome karyotype among women with repeated- miscarry age[J]. Hum Reprod,2004,19( 11 ) : 2644 -2647.