Effect of dexamethasone and betamethasone on fetal heart rate variability in preterm labour: a randomised study

OBJECTIVE: To compare the effects of betamethasone and dexamethasone on fetal heart rate in appropriately grown fetuses. METHODS: Eighty-two pregnant women (97 fetuses) with preterm labour were randomly allocated to receive betamethasone (n=42) or dexamethasone (n=40) for fetal lung maturation in a nonblinded fashion. Computerised cardiotocogram (CTG) parameters were compared before, during and after treatment. RESULTS: A decrease in fetal heart rate variability was found with betamethasone but no significant changes were found with dexamethasone. Fetal heart rate variability returned to pre-treatment values within a week after cessation of treatment with betamethasone. Neonatal outcome was similar in the two groups. CONCLUSIONS: These findings might prove useful in the management of compromised fetuses with decreased fetal heart rate variability in which the CTG should be used together with other parameters to assess fetal wellbeing during corticosteroid treatment. Dexamethasone may be preferable as the drug of choice since it was associated with significantly less alteration in fetal heart rate variability compared with betamethasone.