Maternal angiotensin sensitivity and fetal Doppler umbilical artery flow waveforms

The angiotensin pressor response was investigated in normotensive pregnancies which had umbilical Doppler flow velocity waveforms suggestive of placental vascular disease. Of the 36 pregnancies studied at between 24 and 38 weeks gestation, 18 had a positive response to the angiotensin pressor test, these women were delivered earlier (35.3 vs 38.5 weeks, P = 0.015), had a lower mean birthweight centile (14 vs 36, P less than 0.001) and higher frequency of fetal distress in labour (40% vs 7%, P = 0.06) when compared with the 18 women who had a negative response. The Doppler umbilical systolic-diastolic (S-D) ratio decreased with gestation in the negative group, suggesting continuing placental growth and vascular expansion, whereas the S-D ratio increased in the positive group (P less than 0.001), indicative of vascular obliteration. We suggest that the positive angiotensin pressor response is primarily associated with the placental vascular pathology. Angiotensin infusion had no acute effect on maternal uteroplacental or fetal umbilical artery flow velocity waveforms.