Protocol for measurement of mean arterial pressure at 10-40weeks' gestation

The study aimed to identify the simplest protocol for the measurement of mean arterial pressure (MAP) across 10-40weeks' gestation. 2726 women with uncomplicated singleton pregnancy attending for their routine hospital visit between 10 and 40weeks' gestation were recruited prospectively. The blood pressure (BP) was measured according to the National Heart Foundation of Australia (NHFA) protocol using automated devices. Linearizing regression models were determined for MAP derived from single, repeat and average measurements taken in the left and right arms using the same polynomial power of the best fit model determined using the NHFA protocol. Z-scores were used to compare the differences between the smoothed 50th percentiles. The first measurements taken in the left and right arms were on average 0.15SD and 0.12SD, respectively, higher than those obtained from the NHFA protocol. The second measurements taken in the left and right arms were both 0.26SD lower than the first measurement taken in the same arm and these values were lower than those from the NHFA protocol. The median MAP determined by the protocol of the average of two measurements taken in both arms was similar to the median MAP determined using the NHFA protocol (Z-score 0.0194SD). MAP derived by the average of two measurements in both arms had a quadratic relationship with gestation, with the measurement being the lowest in the mid-trimester. In conclusion, our study has demonstrated that at 10-40weeks' gestation, BP recordings can be obtained by a simpler protocol using the average of two measurements in both arms.