The effect of steroids on the biophysical profile and Doppler indices of umbilical and middle cerebral arteries in healthy preterm fetuses.

OBJECTIVE: To examine the effect of antenatal steroids on the biophysical profile and the Doppler parameters of umbilical and middle cerebral arteries of healthy fetuses. STUDY
DESIGN: Thiry-five singleton pregnancies between the gestational ages of 28 and 34 weeks, who received two consecutive doses of betamethasone 24h apart to accelerate pulmonary maturation were prospectively studied. Fetal biophysical profile and Doppler assessment were performed at 0 (pre-steroid), 24, 48, 72, 96 and 120 h after the administration of first dose. We compared the percentage of the fetuses with biophysical parameters present for each of the five components of the biophysical profile and the Doppler indices, using Cochran's Q-test, Friedman's test and one way analysis of variance of repeated measures where appropriate. The statistical significance was defined as P<0.05.
RESULTS: The mean delivery time was 36.9(+/-1.8) weeks. There was a statistically significant difference in the frequency of the following findings in the pre- compared to post-steroid measurements: absence of body movements (48 h, P<0.05), non-reassuring fetal heart rate tracings (24, 48 and 72 h, P<0.05) and absence of breathing movements (24, 48 and 72 h, p<0.05). Initially none of the biophysical profile score was <or=6, whereas at 24, 48 and 72 h, 13.3, 76.7, 16.7% of them, respectively, were <or=6 (P<0.05). None of the Doppler indices was found to be affected by the steroid administration.
CONCLUSION: Maternal betamethasone administration can cause a significant but transient, reduction in biophysical profile scores, however the middle cerebral and umbilical artery Doppler indices were found to be unaffected suggesting the reliability of this modality for the evaluation of the fetuses previously exposed to the antenatal steroids.