Objective: To evaluate and quantify the effect of glucocorticosteroid administration on fetal movements and biophysical profile scores.Methods: Eighteen women at 32-34 weeks' gestationwere enrolled. Inclusion criterion was an uncomplicated singleton pregnancy not considered to be at high risk. Patients participated for 3 consecutive days. On day 1, the patients underwent a baseline biophysicalprofile including a non-stress test followed by a 12-mg betamethasone intramuscular injection. On day 2, the patients received a non-stress test and a second dose of betamethasone. On day 3, a biophysicalprofile with non-stress test was performed. Maternal counts of fetal kicks were also recorded before, during and after the study period. Each test was conducted at approximately the same time of day tocontrol for diurnal variation. Comparison was made between pre-betamethasone biophysical profile scores and fetal movement and post-betamethasone biophysical profile scores and fetal movement.Results:Biophysical profile scores were reduced in 28% of the study population after betamethasone administration (p < 0.05). Amniotic fluid index on day 3 was decreased from baseline in 72% of patientsafter betamethasone administration (p < 0.05). Forty-four per cent of patients reported a decrease in fetal movement. Of these patients, 87% had a decreased amniotic fluid index when comparedto baseline (p < 0.05).Conclusions: Fetal movements and breathing motion were decreased after glucocorticosteroid administration, as evidenced by biophysical profile scores and kickcounts. The decrease in the amniotic fluid index observed after glucocorticosteroid administration may have been the result of decreased fetal breathing and, therefore, decreased efflux of alveolar fluidinto the amniotic sac.