4Palomaki GE,Knight GJ,McCarthy JE,et al.Maternal serum screening for Down syndrome in the United States:a 1995 survey. American Journal of Obstetrics and Gynecology . 1997
5Biagiotti R,Brizzi L,Periti E,et al.First trimester screening for Down’ s syndrome using maternal serum PAPP-A and free beta-hCG in combination with fetal nuchal translucency thickness. British Journal of Obstetrics and Gynaecology . 1998
6de Graaf IM,Pajkrt E,Bilardo CM,et al.Early pregnancy screening for fetal aneuploidy with serum markers and nuchal translucency. Prenatal Diagnosis . 1999
7Macintosh MC,Brambati B,Chard T,et al.First-trimester maternal serum Schwangerschafts protein 1 ( SP1 ) in pregnancies associated with chromosomal anomalies. Prenatal Diagnosis . 1993
8Wald NJ,Kennard A,Watt HC,et al.Value of maternal serum unconjugated oestriol measurement in prenatal screening for Down’s syndrome. Prenatal Diagnosis . 1994
9Agrawal YP,Ylikangas P,Parviainen MT,et al.Flow cytometric method to measure urea-resistant alkaline phosphatase from blood neutrophils for use in the prenatal screening of Down’s syndrome. Prenatal Diagnosis . 1994
10Qin QP,Christiansen M,Nguyen TH,et al.Schwangerschaftsprotein 1 (SP1) as a maternal serum marker for Down syndrome in the first and second trimesters. Prenatal Diagnosis . 1997
2Wald N J, Densem JM, Smith D, et al. Four marker serum screening for Down syndrome. Prendt Diagn, 1994,14:707.
3Pedersen NB,Alfihan H,Arends J,et al. A new simple and rapid assay for AFP and the free β - hCG in screening for Down syndrome. Clin Genet, 1994,45 : 1.
4Haddow J. Prenatal screening for open neural tube defect Down syndrome and other major fetal disorder. Semin perinatol,1990,14:488.
5Edith YC, David AL, Arthur MZ, et al. A prospective evaluation of a second -trimester screening test for fetal Down syndrome using maternal serum AFP,hCG and μ E3. Obstet Gynecol, 1993,81 ( 1 ) :72 -76.
3Wald NJ, Cuckle HS, Densem JW, et al. Maternal serum screening for Down' s syndrome in early pregnancy[J]. BMJ, 1988,297:883-887.
4Haddow JE, Palomaki GE, Knight GJ, et al, Prenatal screening for Down's syndrome with use of maternal serum markers[J]. N Engl J Mcd, 1992,327:588-593.