Betamethasone-Associated Changes in Umbilical Artery Flow Velocity Waveforms in Multiple Pregnancies With Umbilical Artery Absent End Diastolic Flow

Abstract

Glucocorticoids reportedly temporarily restore the flow velocity waveform in the umbilical artery in singleton pregnancies in which there is no end diastolic flow in this vessel. The present study asked whether similar changes take place in multiple pregnancies when 1 fetus has absent end diastolic flow in the umbilical artery. Twenty-four twin or triplet pregnancies complicated by umbilical artery absent end diastolic flow in 1 of the fetuses were accessed in the years 1996–2002. All women received 2 doses of 11.4 mg betamethasone at a 24-hour interval in an attempt to prevent preterm delivery. They were admitted to the hospital for intensive fetal observation that included daily ultrasound studies of the umbilical artery flow velocity waveform. Six cases diagnosed as twin-to-twin transfusion were excluded. Sixteen of the remaining pregnancies were twins, half of them monochorionic diamniotic, and half dichorionic diamniotic. Two trichorionic triplets completed the study population. Only 1 fetus in each pregnancy had an absent umbilical artery flow velocity waveform; the cofetuses all had normal waveforms. Three women had gestational hypertension and 1 each had insulin-dependent diabetes and essential hypertension. The diagnosis was made at a median gestational age of 210.5 days. Betamethasone treatment was accompanied by a return of end diastolic flow in 9 of the 18 pregnancies; it persisted for a median time of 5 days. No deliveries took place before end diastolic flow stopped. Neither chorionicity nor gestational age at diagnosis influenced the response to betamethasone. All cofetuses had forward end diastolic flow within the normal range for gestational age. Median birth weight was significantly lower when end diastolic flow did not respond to betamethasone (1172 g vs. 1793 g). As is the case for singleton pregnancies, betamethasone treatment is associated with a transient return of umbilical artery end diastolic blood flow in affected fetuses of multiple pregnancies.