3Gooudas VT,Hammitt DG,Damario MA,et al.Blood on the embryo transfe r catheter is associated with decreased rates of embryo implantation and clinica l pregnancy with the use of in vitro fertilization-embryo transfer[J].Fertil Steril,1998,70:878-882
4Visser DS,Fourie F,Kruger HF.Multiple attempts at embryo transfer: Effect on pregnancy outcome in an in vitro fertilization and embryo transfer pro gramme[J].J Assist Reprod Genet,1993,10:37-43
5Daya S,Kohut J,Gunby J,et al.Influence of blood clots in the cumul us on oocyte fertilization and cleavage[J].Hum Reprod,1990,5:744-774
6Dorn C,Reinsberg J,Schlebusch H,et al.Serum oxytoin concentration during embryo transfer procedure[J].Eur J Obstet Gynecol Reprod Biol,1999,87: 77-80
7Ghazzawi IM,A1-Hasani S,Karaki R,et al.Transfer technique and cat h eter choice influence the incidence of transcervical embryo expulsion and the ou tcome of IVF[J].Hum Reprod,1999,14:667-682
4Johnson SP, Sebire NJ, Snijders R J, et al. Ultrasound screening for anencephaly at 10 - 14 weeks of gestation[ J]. Ultrasound Obstet Gy- necol, 1997 Jan,9( 1 ) : 14 -6.
5Salvador J, Arigita M, Carreras E, et al. Evolution of prenatal detec- tion of neural tube defects in the pregnant population of the city of Barcelona from 1992 to 2006[J]. Prenat Diagn, 2011 Dec,31 (12): 1184 -8.
6Beinder E, Grtiner C, Erhardt I, et al. The exencephaly - anenceph- aly sequence. Ultrasound diagnosis in early pregnancy [ J ]. Ultras- chall Med, 1995 Aug, 16 (4) : 192 - 5.
7Ben- Ami I, Edel Y, Barel O, et al. Do assisted conception twins have an increased risk for anencephaly? [ J ]. Hum Reprod, 2011 Dec,26 (12) : 3466 -71.