title: The variables affecting nuchal skin-fold thickness in mid-trimester.
abstract: OBJECTIVE
  To find out variables that have an effect on the measured values of nuchal skin-fold thickness (NT) and to formulate a regression equation on the basis of those variables.
  
  
  METHODS
  The data on gestational age (GA), cephalic index (CI), presentation (Pr, vertex or breech), and the presence or absence of nuchal cord (NC) were collected prospectively on 548 normal singleton fetuses between 16 and 24 weeks gestation, and independent correlation of those variables with NT was calculated by multiple regression analysis and a regression equation was produced.
  
  
  RESULTS
  GA had positive correlation and CI had negative correlation with NT. The nuchal skin-fold was thicker among fetuses with breech presentation rather than those with vertex presentation and increased in the presence of nuchal cord. We calculated the expected NT through these observations: for fetuses presenting vertex, NT = 5.608 + 0.243GA - 0.066CI + NC* and for breech, NT = 2.803 + 0.392GA - 0.066CI + NC*.
  
  
  CONCLUSIONS
  This is the first report, which takes GA, CI, Pr, and NC for correlation factors with NT as a whole. These equations and further studies on determining the cutoff values of the nuchal skin-fold thickness may improve the sensitivity and specificity for the detection of Down syndrome and enable to minimize unnecessary invasive procedures such as amniocentesis or cordocentesis.
authors.affiliation: Department of Obstetrics and Gynecology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: P R
authors.initials: PR
authors.lastname: Lee
authors.forename: H S
authors.initials: HS
authors.lastname: Won
authors.forename: J Y
authors.initials: JY
authors.lastname: Chung
authors.forename: H J
authors.initials: HJ
authors.lastname: Shin
authors.forename: A
authors.initials: A
authors.lastname: Kim
mesh_terms: D000328:Adult; D001946:Breech Presentation; D002508:Cephalometry; D005260:Female; D006801:Humans; D009333:Neck / Q000000981:diagnostic imaging* / Q000196:embryology / Q000473:pathology; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011446:Prospective Studies; D012044:Regression Analysis; D016216:Ultrasonography, Prenatal; D014470:Umbilical Cord / Q000473:pathology