Changes in umbilical artery flow velocity waveforms following maternal administration of betamethasone.

In a retrospective cohort study we have previously shown that administration of betamethasone to women with a pregnancy complicated by absent end-diastolic flow in the umbilical artery (UA) is associated with altered UA flow velocity waveforms. To examine this phenomenon further we undertook a prospective study of 30 similar singleton pregnancies. Umbilical artery FVWs were recorded before and after betamethasone administration using real-time pulsed wave colour flow Doppler. The results of this prospective cohort were similar to those of the retrospective study allowing pooling of the data. Of the 55 total pregnancies with umbilical artery AEDF studied betamethasone administration was associated with the return of end-diastolic flow in 39 (71 per cent; 95 per centCI: 59-83 per cent). The median (range) duration of this change was 3 (1-10) days. There is no evidence that this change has either a beneficial or detrimental effect on foetal health. Administration of betamethasone to women with a pregnancy complicated by umbilical artery AEDF is associated with the transient return of end-diastolic flow in most cases. While the mechanisms underlying this effect are yet to be fully elucidated it has implications for foetal surveillance in these high-risk pregnancies.