title: Nuchal translucency in pregnancies conceived after assisted reproduction technology.
abstract: OBJECTIVE
  Nuchal translucency is one of the important markers in the first trimester during antenatal screening for fetal Down's syndrome. With the observation of alterations in biochemical markers in pregnancies conceived after assisted reproduction, this review presents current information related to the thickness of nuchal translucency in these pregnancies.
  
  
  RESULTS
  Early small studies did not demonstrate any discrepancy in the thickness of nuchal translucency in fetuses from assisted reproduction and from spontaneous pregnancies, but there has been recent evidence to suggest an increased level of nuchal translucency in singletons from various modes of assisted-reproduction technology. Nuchal translucency in twins following assisted reproduction did not, however, show a similar increase. Although the effect of chorionicity was not specifically addressed, nuchal translucency thickness in twins born after assisted reproduction was reported to be comparable to that in spontaneous singletons. It is possible that singletons and twins after assisted reproduction exhibit different antenatal behavior and pregnancy courses.
  
  
  CONCLUSIONS
  Similar to other biochemical markers of fetal Down's syndrome, nuchal translucency is increased in singletons after assisted-reproduction technology. Further studies on twin pregnancies, in particular dichorionic twins, are necessary before conclusive evidence can be drawn for multiple pregnancies.
authors.affiliation: Department of Obstetrics and Gynaecology, University of Hong Kong, Hong Kong. pwhui@graduate.hku.hk
authors.forename: Pui Wah
authors.initials: PW
authors.lastname: Hui
authors.forename: Chin Peng
authors.initials: CP
authors.lastname: Lee
authors.forename: Mary Hoi Yin
authors.initials: MH
authors.lastname: Tang
authors.forename: Pak Chung
authors.initials: PC
authors.lastname: Ho
mesh_terms: D004314:Down Syndrome / Q000175:diagnosis* / Q000503:physiopathology; D005260:Female; D006801:Humans; D048208:Nuchal Translucency Measurement / Q000706:statistics & numerical data*; D011247:Pregnancy; D011272:Pregnancy, Multiple; D027724:Reproductive Techniques, Assisted / Q000009:adverse effects*; D014427:Twins