title: Time of perinatal immunization, thimerosal exposure and neurodevelopment at 6 months in breastfed infants.
abstract: OBJECTIVE
  Brazilian newborns immunized with hepatitis-B (thimerosal containing vaccine, TCV) receive the first dose within 24 h if delivered in public hospitals, but at a later time if born in private hospitals. We compared neurodevelopment (ND) in infants born in a state hospital (immunized within 24 h) and in privately run hospitals (immunized 2-4 days postnatally).
  
  
  METHODS
  We used the Gesell Developmental Schedules in 82 healthy exclusively breastfed infants at 6 months to assess motor skills, language development, comprehension capacity and social skills.
  
  
  RESULTS
  Compared to the group immunized 2-4 days after hospital discharge, the group immunized within 24 h showed no significant difference in ND delays. Despite the variation in gestational age (range 36-42 weeks) and TCV-ethylmercury (EtHg) dose (5.7-11.3 microg Hg/kg b.w.) at birth, time of exposure to TCV showed no significant association with ND. Gesell Developmental Score was not significantly correlated with total parenteral EtHg/unit of body mass neither with the relative increase in hair-Hg (as an additional challenge to prenatal Hg exposure).
  
  
  CONCLUSIONS
  In breastfed infants, differences in early exposure to TCV-EtHg cannot portend clinical neurodevelopment delays at 6 months. We speculate that breastfeeding remains a significant strategy to improve central nervous system protection of infants facing early exposure challenges.
authors.affiliation: Fundação Universidade Federal de Rondônia, Porto Velho, RO, Brasil.
authors.forename: Rejane C
authors.initials: RC
authors.lastname: Marques
authors.forename: José G
authors.initials: JG
authors.lastname: Dórea
authors.forename: Angelo G
authors.initials: AG
authors.lastname: Manzatto
authors.forename: Wanderley R
authors.initials: WR
authors.lastname: Bastos
authors.forename: José V E
authors.initials: JV
authors.lastname: Bernardi
authors.forename: Olaf
authors.initials: O
authors.lastname: Malm
mesh_terms: D001835:Body Weight; D001938:Brazil; D001942:Breast Feeding; D002658:Developmental Disabilities / Q000139:chemically induced*; D005035:Ethylmercury Compounds / Q000008:administration & dosage / Q000009:adverse effects*; D005260:Female; D017325:Hepatitis B Vaccines / Q000008:administration & dosage / Q000737:chemistry; D006801:Humans; D007115:Immunization Schedule; D007231:Infant, Newborn; D008297:Male; D020714:Maximum Tolerated Dose; D009483:Neuropsychological Tests; D011310:Preservatives, Pharmaceutical / Q000008:administration & dosage / Q000009:adverse effects*; D013849:Thimerosal / Q000008:administration & dosage / Q000009:adverse effects*; D013997:Time Factors
chemical_list: D005035:Ethylmercury Compounds; D017325:Hepatitis B Vaccines; D011310:Preservatives, Pharmaceutical; D013849:Thimerosal