BLOOD-PRESSURE AND HEART-RATE AT REST AND DURING STANDING IN PREGNANCY

This study was designed to answer three questiones: 1. Is there a change in systolic blood pressure, diastolic blood pressure and heart rate during pregnancy? 2. Are there alterationes of these parameters during standing? 3. Is there a relationship between mean arterial blood pressure and heart rate at rest and during standing? In a randomized study 161 clinically healthy pregnant women between 8th and 41st week of pregnancy were tested with a modified orthostatic test over defined time periods during pregnancy. Systolic and diastolic blood pressure and heart rate were registered in one minute intervals over a 30 minute period with an automatic Dinamap measuring device. This period was subdivided in a 10 minutes lying period, 10 minutes standing period followed by a 10 minutes lying period. There was a marked increase in systolic and diastolic blood pressure at rest with the beginning of the 34th week of gestation (p < 0.05 and p < 0.01). Despite this, maternal heart rate continued to rise over the whole course of pregnancy (p < 0.01). Furthermore, women with a fall in heart rate on standing were only seen in late pregnancy. Finally, pregnant women with a low mean arterial blood pressure (less-than-or-equal-to 85 mmHg) did not experience a fall in blood pressure on standing more frequently than normal controls (>85 mmHg). We conclude that a fall in blood pressure on standing is not dependent on blood pressure at rest during pregnancy.