title: Thymic size in preterm neonates: a sonographic study.
abstract: OBJECTIVE
  To assess the variation in size of the thymus in vivo in preterm neonates and to identify relations between thymic size and gestational age (GA), birthweight, occurrence of postnatal infections and maternal alcohol and tobacco intake during pregnancy.
  
  
  METHODS
  Eighty preterm neonates with a GA between 24 and 36 wk, and a birthweight between 490 and 4110 g were examined between days 0 and 19 after birth. The thymic size was assessed by sonography as a volume estimate, the so-called thymic index (Ti). The median Ti was 5.2 (1.2-17.9). Ti was positively correlated with birthweight and GA and negatively correlated with occurrence of postnatal infection (p < 0.01, p = 0.03, p = 0.05, R2 = 0.68). A correlation between thymic size and maternal alcohol and tobacco intake was not demonstrated.
  
  
  CONCLUSIONS
  It is possible to assess the size of the thymus by sonography in very low-birthweight and preterm neonates. A normal range for Ti in preterm neonates has been established. The sonographic method is a safe and effective technique for measuring the size of the thymus in preterm infants.
authors.affiliation: Department of Paediatrics, Hvidovre Hospital, University of Copenhagen, Denmark. d.jeppesen@dadlnet.dk
authors.forename: D L
authors.initials: DL
authors.lastname: Jeppesen
authors.forename: H
authors.initials: H
authors.lastname: Hasselbalch
authors.forename: S D
authors.initials: SD
authors.lastname: Nielsen
authors.forename: T U
authors.initials: TU
authors.lastname: Sørensen
authors.forename: A K
authors.initials: AK
authors.lastname: Ersbøll
authors.forename: N H
authors.initials: NH
authors.lastname: Valerius
authors.forename: C
authors.initials: C
authors.lastname: Heilmann
mesh_terms: D000428:Alcohol Drinking / Q000453:epidemiology; D001424:Bacterial Infections / Q000150:complications; D005260:Female; D005315:Fetal Diseases; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D011247:Pregnancy; D011248:Pregnancy Complications; D011297:Prenatal Exposure Delayed Effects; D012907:Smoking / Q000453:epidemiology; D013950:Thymus Gland / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D014463:Ultrasonography