“White Coat” Hypertension During Pregnancy

Objective: This study attempted to determine whether mildly elevated blood pressure during late pregnancy showed the “white coat” phenomenon, with recordings outside the office being below those during a recent clinic visit.Methods: The study group consisted of healthy, previously normotensive patients whose blood pressures during the most recent office visit were elevated on recordings taken initially by a nurse, and then by a physician. Each patient's blood pressures were then recorded automatically by an ambulatory blood pressure monitor (Space Labs 90207) for an average of 106 measurements (over 19 h) per subject. The computer-generated diastolic, systolic, and mean arterial pressure recordings for the next day were averaged for the daytime and nighttime, then compared to those obtained in the recent clinic visit.Results: Thirty (8.0%) of 377 patients followed consecutively in a low-risk clinic had elevated blood pressures during an office visit. In 27 (90.0%) patients, the averaged blood pressures outside the clinic were below those measured in the office. Systolic readings of 140 mm Hg or greater were present in 8.8% (280 of 3181) of ambulatory recordings, while diastolic readings of 90 mm Hg or greater were found in 7.9% (251 of 3181). In no case were averaged blood pressures at home higher than those in the clinic, during the daytime or nighttime hours.Conclusion: This form of mild hypertension during pregnancy is frequently specific to a clinic visit and may lead to unnecessary treatment of hypertension.