The effect of hospitalisation on ambulatory blood pressure in pregnancy

Twenty-four-hour ambulatory blood pressure monitoring was performed on 40 women (20 hypertensive, 20 normotensive) on a hospitalised and non-hospitalised day. Mean blood pressure differences were calculated for the awake, sleeping and 24-hour periods on both days.

Mean heart rate was higher at home (1.79, p = 0.04) than in hospital, but there were no significant differences in mean systolic (1.30 mmHg, p = 0.06), diastolic (0.78 mmHg, p = 0.21) or mean arterial blood pressure (0.81 mmHg, p = 0.19) between the hospitalised and non hospitalised day for the group overall. Nevertheless, the range of individual responses was wide (-8.5 mmHg to 15.4 mmHg mean arterial blood pressure). Hypertensive women receiving antihypertensive therapy had significantly greater differences in mean arterial blood pressure between the hospital and non-hospital day when compared to the rest of the group (5.8 mmHg, compared to 3.3 mm Hg, p = 0.02).

Although hospitalisation does not significantly lower blood pressure in pregnant women as a group, women receiving antihypertensive therapy demonstrate significant differences in blood pressure between hospital and home. Based on conventional blood pressure measurements alone, these women may be at risk of either under treatment, or over treatment, of blood pressure.