title: Fetal growth influences lymphocyte subset counts at birth: the Generation R Study.
abstract: BACKGROUND
  Preterm born and low-birth-weight infants are at risk for severe infections in infancy. It has been suggested that these infants have an immature immune system.
  
  
  OBJECTIVE
  To assess the associations of gestational age, birth weight and fetal growth with absolute lymphocyte subset counts at birth.
  
  
  METHODS
  This study was conducted in 571 infants participating in the Generation R Study, a population-based prospective cohort study from fetal life onwards. Gestational age and birth weight were obtained from midwives and hospital registries. Fetal growth was defined as increase in weight between late pregnancy and birth. Lymphocytes and T lymphocyte subset counts in cord blood were determined by 6-color flow cytometry. Multivariate linear regression models with adjustment for gender, maternal education, smoking, alcohol use, fever and mode of delivery were applied.
  
  
  RESULTS
  Per week increase of gestational age, T, B and NK lymphocyte counts increased with 3, 5 and 6%, respectively (p < 0.05). Helper, cytotoxic and naive T lymphocyte counts increased with 3, 4 and 5%, respectively (p < 0.05), but memory T lymphocyte counts did not. Increased birth weight and fetal growth were significantly associated with higher B lymphocyte counts, independent of gestational age, but not with the other lymphocyte subset counts.
  
  
  CONCLUSIONS
  Lymphocyte subset counts increase with prolonged gestation, suggesting an ongoing development of the immune system. Birth weight and fetal growth seem to influence only B lymphocyte counts.
authors.affiliation: The Generation R Study Group, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Liesbeth
authors.initials: L
authors.lastname: Duijts
authors.forename: Liesbeth E
authors.initials: LE
authors.lastname: Bakker-Jonges
authors.forename: Joost A M
authors.initials: JA
authors.lastname: Labout
authors.forename: Vincent W V
authors.initials: VW
authors.lastname: Jaddoe
authors.forename: Albert
authors.initials: A
authors.lastname: Hofman
authors.forename: Eric A P
authors.initials: EA
authors.lastname: Steegers
authors.forename: Jacques J M
authors.initials: JJ
authors.lastname: van Dongen
authors.forename: Herbert
authors.initials: H
authors.lastname: Hooijkaas
authors.forename: Henriëtte A
authors.initials: HA
authors.lastname: Moll
mesh_terms: D000328:Adult; D001402:B-Lymphocytes / Q000166:cytology / Q000502:physiology*; D001724:Birth Weight / Q000502:physiology; D005260:Female; D005312:Fetal Blood / Q000166:cytology; D047109:Fetal Development / Q000502:physiology*; D020567:Fetal Weight / Q000502:physiology; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D018655:Lymphocyte Count; D008297:Male; D011247:Pregnancy; D011446:Prospective Studies; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000502:physiology*; D055815:Young Adult