title: [Factors affecting the clinical pregnancy rate in an in vitro fertilization and embryo transfer program].
abstract: OBJECTIVE
  To analyze the various factors in an in vitro fertilization and embryo transfer (IVF-ET) program which may affect the clinical pregnacy rate.
  
  
  METHODS
  A retrospective study was done on 559 IVF-ET cycles from 1992-Nov. 1995. The indication for treatment was bilateral tubal blockage. The chi 2 analysis of single factor variants with SPSS-PC + V3.0 was used for statistics.
  
  
  RESULTS
  The overall clinical pregnancy rate in 559 cycles was 21.6%. The cause of tubal blockage due to tuberculoses consisted of 28.4%, and 34.9% of secondary sterility had the history of artificial abortion. The changes of environment, the different causes of tubal blockage, the history of previous intrauterine pregnancy did not affect the clinical pregnancy rate. When the number of embryos transferred increased to 5, the clinical pregnancy rate was highest 32.5%. The cumulative embryo score or embryo quality was related significantly with clinical pregnancy rate.
  
  
  CONCLUSIONS
  The number and quality of embryos transferred are important factors affecting the clinical pregnancy rate. However, measures to prevent high-order multiple pregnancy and studies on the survival potential of embryos besides their morphology should be emphasized.
authors.affiliation: Third Clinical Medical College, Beijing Medical University.
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.forename: Z
authors.initials: Z
authors.lastname: Wei
authors.forename: P
authors.initials: P
authors.lastname: Liu
mesh_terms: D006063:Chorionic Gonadotropin / Q000097:blood; D004624:Embryo Transfer; D005184:Fallopian Tube Diseases / Q000382:microbiology; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D007247:Infertility, Female / Q000209:etiology; D018873:Pregnancy Rate; D012189:Retrospective Studies
chemical_list: D006063:Chorionic Gonadotropin