No effect of experimental noise exposure on human pregnancy. The effect of experimental noise exposure (15 minutes of 90-dB white noise via headphones) was examined on systolic, diastolic, and mean arterial pressures; heart rate; and stress hormones (ACTH, cortisol, prolactin, epinephrine, and norepinephrine) in normotensive and hypertensive pregnant women. No significant effects induced by noise exposure could be registered in these variables. Fetal and uterine blood circulation was also examined with a duplex pulsed Doppler system. No changes were seen on the fetal side as measured from the descending aorta in blood flow velocity (cm/second) or pulsatility or resistance indexes in either normotensive or hypertensive pregnancy. The only change observed was an increase in fetal heart rate in normotensive pregnancy. However, this increase could not be confirmed by cardiotocographic registration and is not clinically important. Uterine blood circulation was recorded from the proximal uterine artery on the placental side, and no effect of exposure was seen on pulsatility or resistance indexes. 