Objective: To examine if maternal blood pressure is directly related to the presence and severity of uteroplacental vascular pathology in nonpreeclamptic preterm birth.
Methods: 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.
Results: 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.
Conclusion: In nonpreeclamptic prematurity, mean maternal admission blood pressure is directly related to the severity of placental vascular pathology.