Effect of antenatal betamethasone and dexamethasone administration on fetal heart rate variability in growth-retarded fetuses.

Purpose: To study the effect of betamethasone and dexamethasone on fetal heart rate in 55 growth-retarded fetuses.
Material and Methods: Fifty-five fetuses with intrauterine growth retardation were exposed in utero to betamethasone (group 1, n = 32) or dexamethasone (group 2; n = 17). Six fetuses received both steroids alternatively at weekly intervals. Computerized cardiotocograms were recorded and analyzed retrospectively. Traces were obtained before, 1 day, 2 days and 4-7 days after treatment was started.
Results: One day after treatment was started, both steroids were associated with an initial increase in fetal heart rate variation that was higher with dexamethasone. Short-term variation was significantly decreased during the betamethasone course. All parameters returned to their pretreatment values within a week.
Conclusion: Dexamethasone and betamethasone had similar effects compatible with a transient damping effect on fetal heart rate variability that reached significance only with betamethasone.