title: First-trimester screening for Down syndrome in singleton pregnancies achieved by intrauterine insemination.
abstract: OBJECTIVE
  To evaluate whether achieving a singleton pregnancy by IUI affects the results of first-trimester screening for Down syndrome compared to naturally conceived pregnancy.
  
  
  METHODS
  Forty-nine IUI and 3059 naturally conceived singleton pregnancies were included in the study. Ovulation in IUI pregnancies was induced by clomiphene and human menopausal gonadotropin. Progesterone was given after insemination for 2 weeks. Down syndrome screening was performed using a combination of maternal age, fetal nuchal translucency, and maternal serum concentrations of free beta-hCG and PAPP-A during the period of 10-14 weeks' gestation.
  
  
  RESULTS
  In IUI pregnancies, nuchal translucency thickness and the levels of PAPP-A were significantly higher. The values of free beta-hCG were not statistically different between the two groups. The screen-positive rate in IUI pregnancies was significantly higher (14.3% vs. 7.1%).
  
  
  CONCLUSIONS
  Singleton pregnancies achieved by IUI have a higher screen-positive rate. Not only elder maternal age but also exogenous hormones given during the process of ovulation induction and after conception may play an important factor influencing positive screening results.
authors.affiliation: Department of Obstetrics and Gynecology, Taipei Medical Center, Cathay General Hospital, Taipei, Taiwan.
authors.forename: Tsung-Hsuan
authors.initials: TH
authors.lastname: Lai
authors.forename: Su-Chee
authors.initials: SC
authors.lastname: Chen
authors.forename: Ming-Song
authors.initials: MS
authors.lastname: Tsai
authors.forename: Fa-Kung
authors.initials: FK
authors.lastname: Lee
authors.forename: Chi-Feng
authors.initials: CF
authors.lastname: Wei
mesh_terms: D000328:Adult; D001835:Body Weight; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D005820:Genetic Testing; D006801:Humans; D007315:Insemination, Artificial; D008423:Maternal Age; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011296:Prenatal Diagnosis