The association between increased mean arterial pressure and abnormal uterine artery resistance to blood flow during pregnancy.

Objective: To examine the relation between increased mean arterial pressure (MAP) and the uterine artery resistance index (RI) to blood flow in the third trimester of pregnancy. Methods: One hundred consecutive patients in the third trimester whose pregnancies were complicated by hypertensive disorders, with or without proteinuria, had uterine artery resistance to blood flow measured using continuous-wave Doppler. Results: The RI was in the normal range in 20 patients. Unilaterally abnormal RI was found in 32 and bilaterally abnormal RI in 46 (two subjects were excluded from this categorization because measurements were obtained from only one side of the uterus). A MAP below 100 mmHg was associated with a normal RI