title: Does a discrepancy between gestational age determined by biparietal diameter and last menstrual period sometimes signify early intrauterine growth retardation?
abstract: OBJECTIVE
  To assess the association between gestational age estimated from the last menstrual period (GA(LMP)) or from the biparietal diameter (GA(BPD)), and the subsequent birthweight for gestational age.
  
  
  METHODS
  Population-based follow up study.
  
  
  METHODS
  Of 21,936 pregnancies contained in the ultrasound database, 16,387 singleton pregnancies with a reliable last menstrual period date and an ultrasound examination between 12 and 22 weeks of gestation were included.
  
  
  METHODS
  Correlation between: 1) birthweight deviation (birthweight-expected weight for gestation); 2) birthweight; and 3) pregnancy length and (GA(LMP)-GA(BPD)). Relative risk of birthweight < 2,500 g and low birthweight for gestation (> 22% below normal weight) related to five levels of discrepancy between (GA(LMP)-GA(BPD)).
  
  
  RESULTS
  (GA(LMP)-GA(BPD)) was not associated with deviation of birthweight related to GA(BPD). However the risk of low birthweight (< 2,500 g) and low birthweight for gestational age was significantly increased when (GA(LMP)-GA(BPD)) was > 7 days.
  
  
  CONCLUSIONS
  A biparietal diameter smaller than expected from the last menstrual period date is mainly a problem of an error related to estimated time of ovulation. At the same time the relative risk of a low birthweight infant is slightly increased.
authors.affiliation: Department of Ultrasound, and Obstetrics and Gynaecology, Herlev Hospital, University of Copenhagen, Denmark.
authors.forename: T
authors.initials: T
authors.lastname: Larsen
authors.forename: T H
authors.initials: TH
authors.lastname: Nguyen
authors.forename: G
authors.initials: G
authors.lastname: Greisen
authors.forename: G
authors.initials: G
authors.lastname: Engholm
authors.forename: H
authors.initials: H
authors.lastname: Møller
mesh_terms: D000293:Adolescent; D000328:Adult; D001724:Birth Weight; D005260:Female; D005317:Fetal Growth Retardation / Q000175:diagnosis* / Q000000981:diagnostic imaging; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D008423:Maternal Age; D008598:Menstruation; D008875:Middle Aged; D011247:Pregnancy; D012886:Skull / Q000196:embryology*; D016216:Ultrasonography, Prenatal