title: Factors associated with thymic size at birth among low and normal birth-weight infants.
abstract: OBJECTIVE
  To study the effect of gestational and perinatal exposures on thymic size in 366 normal birth weight and 426 low birth weight (LBW) neonates in Guinea-Bissau in West Africa.
  
  
  METHODS
  In a cross-sectional study, thymic size was measured at birth by the use of ultrasound. Information on possible determinants was collected from pregnancy cards, hospital records, and interviews with the mother. We used the log-transformed thymic index and thymus/weight index as outcome measures. Data were analyzed with adjusted linear regression models providing geometric mean ratios (GMRs) with 95% CI.
  
  
  RESULTS
  Determinants of thymic size among normal birth weight infants were pathologic amniotic fluid (adjusted GMR for thymic index: 0.84 [0.74-0.96]) and male sex (GMR: 1.13 [1.06-1.22]). Among LBW infants, birth season (1.11 [1.01-1.22]), maternal body temperature (0.89 [0.79-0.98]), antibiotic treatment at the time of labor (0.84 [0.70-1.00]), number of pregnancy consultations (1.03 [1.00-1.05]), maternal age (0.91 [0.84-0.98]), Apgar score (1.06 [1.03-1.10]), and infant convulsions (0.44 [0.29-0.65]) were all independent determinants of thymic index but not all were determinants of thymus/weight index. Pathologic amniotic fluid and cesarean delivery were associated with thymus/weight index among LBW infants (0.85 [0.75-0.95] and 0.80 [0.67-0.96]) but were only borderline significant for thymic index.
  
  
  CONCLUSIONS
  Exposures mainly related to stress and infections were associated with a smaller thymus, mainly in LBW infants.
authors.affiliation: Research Center for Vitamins and Vaccines (CVIVA), Statens Serum Institut, Copenhagen, Denmark; Department of Clinical Microbiology, Copenhagen University Hospital, Hvidovre, Denmark. Electronic address: h.eriksen@bandim.org.
authors.forename: Helle Brander
authors.initials: HB
authors.lastname: Eriksen
authors.affiliation: Research Center for Vitamins and Vaccines (CVIVA), Statens Serum Institut, Copenhagen, Denmark; Bandim Health Project, INDEPTH Network, Bissau, Guinea-Bissau.
authors.forename: Sofie
authors.initials: S
authors.lastname: Biering-Sørensen
authors.affiliation: Research Center for Vitamins and Vaccines (CVIVA), Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Najaaraq
authors.initials: N
authors.lastname: Lund
authors.affiliation: Bandim Health Project, INDEPTH Network, Bissau, Guinea-Bissau.
authors.forename: Cizete
authors.initials: C
authors.lastname: Correia
authors.affiliation: Bandim Health Project, INDEPTH Network, Bissau, Guinea-Bissau.
authors.forename: Amabelia
authors.initials: A
authors.lastname: Rodrigues
authors.affiliation: Research Center for Vitamins and Vaccines (CVIVA), Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Andreas
authors.initials: A
authors.lastname: Andersen
authors.affiliation: Research Center for Vitamins and Vaccines (CVIVA), Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Ravn
authors.affiliation: Research Center for Vitamins and Vaccines (CVIVA), Statens Serum Institut, Copenhagen, Denmark; Bandim Health Project, INDEPTH Network, Bissau, Guinea-Bissau.
authors.forename: Peter
authors.initials: P
authors.lastname: Aaby
authors.affiliation: Department of Pediatrics, Copenhagen University Hospital, Hvidovre, Denmark.
authors.forename: Dorthe L
authors.initials: DL
authors.lastname: Jeppesen
authors.affiliation: Research Center for Vitamins and Vaccines (CVIVA), Statens Serum Institut, Copenhagen, Denmark; Bandim Health Project, INDEPTH Network, Bissau, Guinea-Bissau; OPEN, Institute for Clinical Research, University of Southern Denmark, Odense, Denmark.
authors.forename: Christine Stabell
authors.initials: CS
authors.lastname: Benn
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001034:Apgar Score; D001831:Body Temperature; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006169:Guinea-Bissau; D006760:Hospitalization; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D016014:Linear Models; D008297:Male; D009929:Organ Size; D011247:Pregnancy; D016032:Randomized Controlled Trials as Topic; D013950:Thymus Gland / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D014463:Ultrasonography
chemical_list: D000900:Anti-Bacterial Agents