title: Fetal versus maternal and gestational age effects of repetitive antenatal glucocorticoids.
abstract: BACKGROUND
  Although single courses of antenatal glucocorticoids decrease respiratory distress syndrome and mortality, repetitive courses of antenatal glucocorticoids are being given to women at risk of preterm delivery without evidence of benefit or appreciation of potential risks.
  
  
  OBJECTIVE
  To evaluate the effects of single and repetitive antenatal glucocorticoid exposures on fetal growth and postnatal lung function in sheep.
  
  
  METHODS
  Pregnant ewes were randomized to three protocols that included one or three doses (at 7-day intervals) of 0.5 mg/kg of betamethasone (beta) given to the ewe or fetus beginning at gestations ranging from 104 to 128 days' gestation with delivery at 125, 135, and 146 days' gestation. Postnatal assessments included measurements of gas exchange, compliance, ventilation efficiency, static lung volume, and lung tissue and alveolar wash saturated phosphatidylcholine.
  
  
  RESULTS
  Single or repetitive maternal beta but not fetal beta caused fetal growth retardation at delivery at 125, 135, and 146 days' gestation. Single-dose fetal beta had no effect on postnatal lung function whereas single-dose maternal beta significantly increased compliance, lung volume, and tissue and alveolar surfactant after preterm delivery. Although three-dose fetal beta improved all indicators of postnatal lung function, three-dose maternal beta resulted in larger responses. The added benefits of repetitive beta relative to a single-dose beta on postnatal lung function after preterm delivery were not as great when therapy was begun later in gestation. Postnatal lung function after delivery at 146 days' gestation (term is 150 days) was improved after repetitive maternal beta at early gestational age.
  
  
  CONCLUSIONS
  In sheep, single or repetitive maternal beta causes growth retardation from 104 to 121 days' gestation and the growth retardation persists to term. In contrast, single or repetitive fetal beta does not cause fetal growth retardation and is less potent at improving postnatal lung function and increasing surfactant pools. There are potential benefits as well as risks for the use of repetitive antenatal glucocorticoids. Randomized, controlled trials in humans are essential given the widespread use of repetitive courses of antenatal glucocorticoids in women at risk of preterm delivery. respiratory distress syndrome, maturation, prematurity, growth retardation, surfactant.
authors.affiliation: Division of Pulmonary Biology, Children's Hospital Medical Center, Cincinnati, Ohio, USA.
authors.forename: A H
authors.initials: AH
authors.lastname: Jobe
authors.forename: J
authors.initials: J
authors.lastname: Newnham
authors.forename: K
authors.initials: K
authors.lastname: Willet
authors.forename: P
authors.initials: P
authors.lastname: Sly
authors.forename: M
authors.initials: M
authors.lastname: Ikegami
mesh_terms: D000818:Animals; D001623:Betamethasone / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D005314:Embryonic and Fetal Development / Q000187:drug effects*; D005260:Female; D005317:Fetal Growth Retardation / Q000139:chemically induced*; D005938:Glucocorticoids / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D007231:Infant, Newborn; D008168:Lung / Q000187:drug effects / Q000196:embryology / Q000502:physiology; D011247:Pregnancy; D011897:Random Allocation; D012127:Respiratory Distress Syndrome, Newborn / Q000517:prevention & control*; D012756:Sheep
chemical_list: D005938:Glucocorticoids; D001623:Betamethasone