DIFFERENCES BETWEEN OFFICE AND 24-HOUR AMBULATORY BLOOD-PRESSURE MEASUREMENT DURING PREGNANCY

Objective: To compare blood pressure (BP) measurements in ambulatory p regnant women with well-taken office readings. Methods: A cohort of 20 9 nulliparous pregnant women who underwent 24-hour ambulatory BP monit oring throughout pregnancy was studied; 62 of these women were also st udied 12 weeks after delivery. In addition, 30 nulligravid, nonpregnan t women were studied as controls. Results: The 24-hour median systolic and diastolic ambulatory pressures were higher than office pressures during pregnancy (the differences between the office and ambulatory sy stolic and diastolic BP measurements were +5 and +5.5 mmHg at 18 weeks , +3 and +6.5 mmHg at 28 weeks, and +5 and +5.5 mmHg at 36 weeks, P < .001). Ambulatory BP showed a consistent rise over the three measureme nt points, resulting in higher levels of pressure at 36 weeks than tho se found 12 weeks after delivery (the difference between ambulatory BP at these measurement points was +5 and +1 mmHg). At the postpartum me asurement point, the relationship between ambulatory and office BP was similar to that in other surveys in nonpregnant women of comparable a ges and in our own control group of nulligravidas (the difference betw een ambulatory and office BPs after delivery was +1.5 and +2 mmHg, a n onsignificant difference). Conclusion: There are important differences between ambulatory and office BPs measured throughout pregnancy, find ings that could not be explained by activity or our present knowledge of cardiovascular hemodynamics in pregnancy. Ambulatory BP readings mu st be considered different entities than office BP readings. Care shou ld be taken in predicting obstetric outcome from the results of ambula tory BP recordings.