Uteroplacental pathology and maternal arterial mean blood pressure in spontaneous prematurity

To examine if maternal blood pressure is directly related to the presence and severity of uteroplacental vascular pathology in nonpreeclamptic preterm birth.

A set of consecutive nonanomalous singleton live births delivered at 22-32 weeks (excluding maternal diabetes mellitus and chronic hypertension) between 1989 and 1994 included 342 cases of spontaneous prematurity (spontaneous premature membrane rupture [PROM], preterm labor with intact membranes [PTL], and nonhypertensive abruption) with mean arterial blood pressure at admission available in the maternal record. Presence and extent of placental lesions were scored.

Mean maternal arterial blood pressure on admission was significantly related to the presence/extent of uteroplacental vascular lesions (P = .01) and to lesions of intraplacental vaso-occlusion (P = .04). These associations were independent of maternal age and gestational age at delivery. Moreover, the summation of uteroplacental and intraplacental vascular lesions into a cumulative placental vascular pathology score was even more significantly correlated with increasing mean blood pressure at admission, suggestive of synergism between these two placental pathologic processes.

In nonpreeclamptic prematurity, mean maternal admission blood pressure is directly related to the severity of placental vascular pathology.