Effect of antenatal betamethasone therapy on maternal-fetal Doppler velocimetry

Background: The effect of antenatal betamethasone on fetal parameters inclu des a transient reduction of FHR variation and of fetal body movements. An effect on maternal-fetal blood flow has also been shown, with non-univocal results. Aims: To evaluate the effect of antenatal betamethasone in third t rimester singleton high-risk pregnancies by Doppler technology. Subjects an d methods: Thirty-six pregnant women who received a full course of betameth asone (12 mg i.m, two times, 24 h apart) were studied. The Doppler examinat ion included the assessment of the pulsatility index (PI) of the umbilical artery (UA PI), the middle cerebral artery (MCA PI) and of resistance index of uterine arteries (Ut RI) before treatment, and 48 and 96 h after second dose of betamethasone. Results: No significant variation was noted in UA P I through betamethasone therapy. MCA PI decreased significantly 48 h from t he last injection of betamethasone (P = 0.002), and returned to basal value s at 96 h. No difference was found for the other Doppler parameters examine d. When serial Doppler studies were analyzed according to the gestational a ge, in the group < 32 weeks' gestation, MCA PI decreased significantly afte r 48 h (P < 0.006) and returned to pre-treatment values after 96 h from the last betamethasone dose. Conversely, no difference was found in Doppler se rial measurements in any of the analyzed districts in the subgroup greater than or equal to 32 weeks. Conclusion: Betamethasone treatment is associate d with a significant, although transient, reduction of MCA PI, especially a t gestational ages < 32 weeks'. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.