B4. Normal and abnormal blood pressures in early pregnancy: are we using the right cut off values?

Abstract

Introduction: Subclinical hypertension has been reported in the first trimester of future hypertensive patients compared to normotensive patients. However, in clinical practice today, a cut off of 140/90 mmHg is still used to discriminate normotension from hypertension during pregnancy. We aim to investigate the most appropriate threshold for early gestational blood pressure values, which allow discriminating pregnant women between those at low or at high risk for gestational hypertensive diseases.

Methods: Singleton pregnancies were included. A standard protocol was used to measure systolic (SBP), diastolic (DBP) and mean arterial pressure (MAP) in supine and standing position, by mode of an oscillometric sphygmomanometer around 12 weeks and 20 weeks of gestation. After delivery, gestational outcome was categorized in normotensive pregnancies (NP) or gestational hypertensive disease (GHD). ROC analysis was used to define the early gestational blood pressure cut off value with best possible performance in predicting GHD. Mann–Whitney U tests at nominal level a <0.05 were performed using SPSS for intergroup comparison.

Results: A total of 780 women were measured at 12 weeks. Of these, 433 pregnant women were reevaluated around 20 weeks. At 12 and 20 weeks, blood pressures in GHD were higher than in NP (Table 1).

Figure 1. (A) Boxplot NP versus GHD of DBP at 12 weeks, where redline indicates the threshold. (B) Boxplot UP versus GHD of DBP at 20 weeks with red line as threshold.

Conclusions: Simple sphygmomanometric blood pressure measurements in standing position under standardized conditions at 12 weeks and 20 weeks has ≥96% negative predictive value for gestational hypertensive disease when DBP cut off is set at 81 and 78 mm Hg, respectively.