Time of perinatal immunization, thimerosal exposure and neurodevelopment at 6 months in breastfed infants.
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.
Marques
Rejane C
RC
Fundação Universidade Federal de Rondônia, Porto Velho, RO, Brasil.
Dórea
José G
JG
Manzatto
Angelo G
AG
Bastos
Wanderley R
WR
Bernardi
José V E
JV
Malm
Olaf
O
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
D005035:Ethylmercury Compounds; D017325:Hepatitis B Vaccines; D011310:Preservatives, Pharmaceutical; D013849:Thimerosal