The effect of betamethasone versus dexamethasone on fetal biophysical parameters.

ABSTRACT

BACKGROUND: Clinical observations suggest that betamethasone reduces maternal perception of fetal movements and short term variability, but that this dose not occur after treatment with dexamethasone. OBJECTIVES: To compare the effect of betamethasone and dexamethasone on fetal biophysical parameters. METHODS: In a randomized, prospective, double blind study, 20 courses of betamethasone and 20 courses of dexamethasone were given in random sequence to patients with imminent preterm labor. During the first 32h after initiation of treatment, fetal movements were counted by the mothers and recorded by ultrasound, and a nonstress test was performed. RESULTS: Betamethasone induced a significant decrease in fetal movements as perceived by the mother and observed by ultrasound. Fetal breathing movements also decreased. Dexamethasone did not change fetal body movements. Neither drug changed the short term variability. CONCLUSIONS: Unlike betamethasone, dexamethasone does not induce a decrease in fetal movements. Dexamethasone might, therefore, be preferred for enhancement of lung maturation in imminent preterm labor.