Arterial blood pressure and posture during pregnancy

Abstract

Abstract 1. 1. In 17 pregnant women the systolic and diastolic blood pressure were significantly lower in the left lateral position than in the sitting or supine position. In only five of these 17 women was the same found for the pulse rate. 2. 2. The systolic blood pressure is significantly related to the duration of pregnancy with patients in both supine and lateral positions. The diastolic blood pressure was very significantly related to the duration of pregnancy in all three positions. This pressure increased after the 26th week in all three positions to fall after labor to the original level. The diastolic blood pressure was less variable than the systolic blood pressure. The pulse rate was very significantly related to the duration of pregnancy in the supine position. It increased gradually until labor and decreased in the puerperium. 3. 3. The measurements on the women in the different positions were always performed in the order: sitting, supine, left lateral position. This systematic order of observation cannot explain the effect of posture mentioned in (1). In a separate investigation with 42 women, where the order of the positions was changed, no effect of the order of measurement could be demonstrated and the effect of posture was again established. 4. 4. The lower arterial blood pressures in the left lateral position can be partly explained by the hydrostatic difference between the level of measurement (right upper arm) and the heart. The concomitant change in pulse rate suggests, however, an involvement of the Bainbridge reflex probably through a better venous filling of the right heart in the lateral position.