title: Reference intervals for the cross sectional area of the umbilical cord during gestation.
abstract: OBJECTIVE
  To establish reference values for the sonographic cross-sectional area of the umbilical cord during gestation and to correlate them with fetal anthropometric parameters.
  
  
  METHODS
  A cross-sectional study was performed involving 312 normal pregnant women at gestational ages 24-39 weeks. Measurement of the cross-sectional area of umbilical cord was performed on a plane adjacent to the insertion of the cord into fetal abdomen. The following anthropometric parameters were calculated: biparietal diameter, head circumference, abdominal circumference and femur length. A polynomial regression analysis identified the curves that were better adjusted to the average and standard deviation according to gestational age. Spearman correlation was used to evaluate the correlation of the cross-sectional area of umbilical cord with fetal anthropometric parameters.
  
  
  RESULTS
  A statistically significant correlation was observed between the cord cross-sectional area and gestational age (r=0.376, P<0.001, CI 95%[0.276; 0.467]).
  
  
  CONCLUSIONS
  The reference values of the cross-sectional area of umbilical cord increased according to gestational age until the 33rd week and are related to parameters of fetal growth.
authors.affiliation: Department of Obstetrics, Sao Paulo's Federal University (Unifesp/EPM), Brazil.
authors.forename: Fernando Alves
authors.initials: FA
authors.lastname: Togni
authors.forename: Edward
authors.initials: E
authors.lastname: Araujo Júnior
authors.forename: Antonio Fernandes
authors.initials: AF
authors.lastname: Moron
authors.forename: Flávio Augusto Prado
authors.initials: FA
authors.lastname: Vasques
authors.forename: Maria Regina
authors.initials: MR
authors.lastname: Torloni
authors.forename: Luciano Marcondes Machado
authors.initials: LM
authors.lastname: Nardozza
authors.forename: Hélio Antonio
authors.initials: HA
authors.lastname: Guimarães Filho
mesh_terms: D000293:Adolescent; D000328:Adult; D000886:Anthropometry; D003430:Cross-Sectional Studies; D005260:Female; D047109:Fetal Development; D006801:Humans; D011247:Pregnancy; D012015:Reference Standards; D014463:Ultrasonography; D014470:Umbilical Cord / Q000000981:diagnostic imaging*