title: Auditory neural maturation after exposure to multiple courses of antenatal betamethasone in premature infants as evaluated by auditory brainstem response.
abstract: OBJECTIVE
  Our goal was to determine if multiple courses of antenatal betamethasone affect auditory neural maturation in 28 to 32 weeks' gestational age infants.
  
  
  METHODS
  A retrospective cohort study was performed to compare auditory neural maturation between premature infants exposed to 1 course of betamethasone and infants exposed to > or = 2 courses of betamethasone. Inclusion criteria included all 28 to 32 weeks' gestational age infants delivered between July 1996 and December 1998 who had auditory brainstem response testing performed (80-dB click stimuli at a repetition rate of 39.9/second) within 24 hours of postnatal life as part of bilirubin-auditory studies. Infants with toxoplasmosis, rubella, cytomegalovirus, herpes infections, chromosomal disorders, unstable conditions, exposure to antenatal dexamethasone, and exposure to < 1 complete course of betamethasone were excluded. Auditory waveforms were categorized into response types on response replicability and peak identification as types 1 through 4 (type 1 indicating most mature). Absolute and interpeak wave latencies were measured when applicable. Categorical and continuous variables were analyzed by using the chi2 test and Student's t test, respectively.
  
  
  RESULTS
  Of 174 infants studied, 123 received antenatal steroids. Of these, 50 received 1 course and 29 received > or = 2 courses of betamethasone. There were no significant differences in perinatal demographics between the 2 groups. After controlling for confounding variables, there was no significant difference in mean absolute wave latencies, mean interpeak latencies, or distribution of response type between the 2 groups. There also was no significant difference in any auditory brainstem response parameters between infants exposed to 1 course of betamethasone (n = 50) and infants exposed to > 2 courses of betamethasone (n = 17).
  
  
  CONCLUSIONS
  Compared with a single recommended course of antenatal steroids, multiple courses of antenatal betamethasone are not associated with a deleterious effect on auditory neural maturation in 28 to 32 weeks' gestational age infants.
authors.affiliation: Department of Pediatrics, Golisano Children's Hospital at Strong, University of Rochester, Rochester, New York, USA. sanjiv_amin@urmc.rochester.edu
authors.forename: Sanjiv B
authors.initials: SB
authors.lastname: Amin
authors.forename: Ronnie
authors.initials: R
authors.lastname: Guillet
mesh_terms: D001623:Betamethasone / Q000008:administration & dosage*; D002530:Cerebellopontine Angle / Q000196:embryology* / Q000254:growth & development; D015331:Cohort Studies; D036861:Delivery, Obstetric; D004305:Dose-Response Relationship, Drug; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects* / Q000502:physiology*; D005260:Female; D005865:Gestational Age; D005938:Glucocorticoids / Q000008:administration & dosage*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D011247:Pregnancy; D011295:Prenatal Care; D011930:Reaction Time / Q000187:drug effects; D012189:Retrospective Studies
chemical_list: D005938:Glucocorticoids; D001623:Betamethasone