Evaluation of the blood pressure load in the diagnosis of hypertension in pregnancy

The use of a set of new end points obtained from ambulatory blood pressure monitoring, in addition to the blood pressure values themselves, has been a dvocated to improve sensitivity and specificity in the diagnosis of hyperte nsion and the evaluation of a patient's response to treatment. Among these parameters is the use of blood pressure load, the percentage of values abov e a given constant reference limit or computed by reference to daytime and nighttime limits. We examined the effectiveness of this parameter as a pote ntial screening test for the detection of hypertension in pregnancy. We ana lyzed 2014 blood pressure series systematically sampled by ambulatory monit oring for 48 consecutive hours every 4 weeks from the first obstetric visit (usually within the first trimester of pregnancy) until delivery of 205 no rmotensive pregnant women and 123 women who developed gestational hypertens ion or preeclampsia. The blood pressure load was obtained as the percentage of values > 140/110/90 mm Hg (systolic/mean arterial/diastolic blood press ure) during active hours or 120/95/80 mm Hg during resting hours, as well a s by comparison with limits obtained by progressively reducing the previous limits by 5 mm Hg, up to a final threshold of 125/95/75 mm Hg (day) and 10 5/80/65 mm Hg (night). Sensitivity for the blood pressure load computed by reference to the highest limits used here is < 55% in all trimesters of pre gnancy. The best results were obtained when 130/100/80 mm Hg (day) and 110/ 85/70 mm Hg (night) were used as references in the third trimester, and whe n the lowest tested limits of 125/95/75 and 105/80/65 mm Hg were used as re ferences in the first and second trimesters (sensitivity always > 73%). The optimum reference limits for calculating the blood pressure load, markedly < 140/90 mm Hg, must be defined as a function of gestational age, in keepi ng with the predictable trends in blood pressure along pregnancy previously documented.