Correct position for BP measurement during pregnancy

Patient: When measuring BP during pregnancy, should I be lying on my left side (as the nurses at the ER had me) or sitting (as suggested in Harrison 17Ed, Part 1, Chapter 7, right at the top)? Please, give me a reference in a gynecology textbook…

Doctor: I do understand your concern. No matter which device is used to measure blood pressure, it must be recognised that blood pressure is a variable haemodynamic phenomenon, which is influenced by many factors. These influences on blood pressure can be significant, often accounting for rises in systolic blood pressure greater than 20 mm Hg, and if they are ignored, or unrecognised, hypertension will be diagnosed erroneously and inappropriate management instituted. According to an article in emedicine – “Blood pressure should be measured in the sitting position, with the cuff at the level of the heart. Inferior vena caval compression by the gravid uterus while the patient is supine can alter readings substantially, leading to an underestimation of the blood pressure. Similarly, blood pressures measured in the left lateral position may yield falsely low values if the blood pressure is measured in the higher arm, unless the cuff is carefully maintained at the level of the heart.” I do hope the information helps, I wish you the best for your pregnancy.