Diurnal blood pressure variation in the evaluation of early onset severe pre-eclampsia.

Objective: To study the association between diurnal variation in blood pressure, the mean daily blood pressure and various complications of pregnancy in patients presenting with severe pre-eclampsia before 34 weeks' gestation.

Study Design: Forty-four women presenting to a tertiary hospital in South Africa with severe pre-eclampsia between 28 and 34 weeks' gestation were managed expectantly for at least 8 days. We measured maternal blood pressure every 30 min with the pregnancy validated Spacelabs 90209 automated blood pressure monitor for 24h periods on alternative days. The mean 24-h diastolic blood pressure measurement, the mean diastolic blood pressure for daytime and nighttime, the day-night blood pressure difference and the night-day ratio were compared with the occurrence of abruptio placentae, gestational age at delivery, neonatal intensive care unit admission, birth weight, abnormal umbilical artery Doppler FVW and reason for delivery.

Results: One hundred and seventy-six 24-h studies were analyzed. The day-night blood pressure difference decreased with increasing mean diastolic blood pressure (r=-0.323, p<0.0001). A combination of normal mean diastolic blood pressure and normal day-night blood pressure difference was associated with increased gestational age and lower caesarean section rates.

Conclusion: The combination of mean diastolic blood pressure and day-night blood pressure difference may be a supplementary measurement of disease severity in early onset severe pre-eclampsia and seems to be of prognostic value.