Ambulatory blood pressure monitoring in normotensive pregnant women.

Ambulatory blood pressure monitoring (ABPM) provides a profile of blood pressure (BP) during daily activities and sleep and could uncover the inter-individual variability of BP. The aims of this study were to establish the normal values of the ABPM during the three trimesters of normal pregnancy, and to compare these values with those obtained in the office. ABPM was carried out on 22 normotensive pregnant women. BP values were compared with those obtained in the office. BP during the third trimester was significantly higher than the BP recorded during the first two gestational periods. In the three trimesters of pregnancy mean ambulatory systolic and diastolic BP were lower than the BP measured in the office in lying and standing positions. On the other hand, mean ambulatory BP (systolic and diastolic) measured during daily activities was not significantly different from the BP measured in the office. Sleeping BP was significantly lower than waking values in all trimesters, while there were not significant differences in the degree of BP fall among the three trimesters. Six women were sequentially studied during the three trimesters of pregnancy and particularly at the 12, 24 and 32 weeks of pregnancy. In these women, a small but significant rise in mean 24 h systolic and diastolic BP was observed at 32 weeks of pregnancy. Sleeping BP was significantly lower than waking values in the three trimesters. No significant difference in the degree of BP fall on the three gestational dates was found. It is concluded that ABPM is a useful tool for the evaluation of BP variability during pregnancy. During normal pregnancy ambulatory BP levels are highest in the day and lowest at night at all gestational ages and increased at the third trimester of pregnancy compared to the values observed during the first two gestational periods.