Inter-arm blood pressure differences in pregnant women

Objective To determine the prevalence of blood pressure inter-arm difference (IAD) in early pregnancy and to investigate its possible association with maternal characteristics. Design A cross-sectional observational study. Setting Routine antenatal visit in a university hospital. Population A total of 5435 pregnant women at 11-14 weeks of gestation. Methods Blood pressure was taken from both arms simultaneously with a validated automated device. Main outcome measures The presence of inter-arm blood pressure difference of 10 mmHg or more. Results The IAD in systolic and diastolic blood pressure was 10 mmHg or more in 8.3 and 2.3% of the women, respectively. Systolic LAD was found to be significantly related to systolic blood pressure and pulse pressure, and diastolic IAD was found to be significantly related to maternal age, diastolic blood pressure and pulse pressure. The systolic and diastolic IAD were higher in the hypertensive group compared with the normotensive group and absolute IAD increased with increasing blood pressure. About 31.0 and 23.9% of cases of hypertension would have been underreported if the left arm and the right arm were used, respectively, in measuring the blood pressure. Conclusions There is a blood pressure IAD in a significant proportion of the pregnant population, and its prevalence increases with increasing blood pressure. By measuring blood pressure only on one arm, there is a one in three chance of underreporting hypertension. Therefore, it would be prudent that during the booking visit blood pressure should be taken in both arms and thus provide guidance for subsequent blood pressure measurements during the course of pregnancy.