Neonatal blood pressures.

Arterial blood pressures were taken by the Doppler ultrasound method in 134 unselected mature neonates (birthweights 2,600-3,900 grams) who were managed in the same manner after birth. Blood pressures were measured at 3-5, 10 and 30 minutes of life and, if indicated, intermittently during the next 24-48 h. Left and right arm pressures were identical or differed by only 1-2 mm Hg. Lower than normal blood pressures were found in 4 groups of infants: those born by cesarean section, those recovering from intrauterine asphyxia, those exposed to maternal anti-hypertensive therapy, and those whose mothers received thiopental within four minutes of delivery. Return of the low pressures to within the normal range was fastest following thiopental induction in the absence of fetal asphyxia and slowest after antihypertensive therapy.