[Doppler echographic study of placental circulation of the fetus of normal and hypertensive mothers].

Foetal blood velocity wave forms, as recorded in chorionic vessels by pulsed Doppler ultrasonography, reflect vascular resistance in foetal placental circulation. The minimal-to-maximal velocity ratio provides an index of vascular conductance; the higher the minimal velocity (positive forward diastolic blood flow), the lower the vascular resistance. In the present study, this index was the same in pregnant women with normal blood pressure (n = 19) and in those with pregnancy-induced hypertension (n = 12); however, it was significantly lowered (p less than 0.001) in pregnant women with essential hypertension (n = 9). In the population of women with normal blood pressure and pregnancy-induced hypertension, a positive correlation (r = 0.71), was found between index value and gestational age, indicating a progressive fall in placental vascular resistance. All placentas from these 31 women were histologically normal except two which showed one single marginal infarct less than 1 cm in diameter. In the group of women with essential hypertension, the 6 placentas examined were pathological, with multiple chronic infarcts, placental growth retardation and maceration. Thus, pulsed Doppler ultrasonography should be used for early detection of placental vascular damage and for improved surveillance of pregnancies complicated by maternal vascular diseases.