Research Article
Vonck S, Oben J, Staelens A
Abstract
Background: Despite reported early subclinical hypertension of women at risk, blood pressures at threshold 140/90 mm Hg are used today to guide prenatal care. We aim to investigate the most appropriate gestation-specific threshold to measure early gestational blood pressures, allowing for a simple stratification between pregnant women at low/high risk for hypertension. Methods: Singleton pregnancies were selected at Clinic Oost-Limburg, Genk, Belgium. 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 and 20 weeks of gestation. After delivery, outcome was categorized in normotensive or hypertensive pregnancies. In a subgroup, routine blood pressures retrieved from prenatal records were compared to standardized blood pressures. ROC analysis was used to define early gestational blood pressure thresholds with best discriminative performance for hypertension. All analyses were done in SPSS software (α ≤ 0.05). Results: A total of 780 women were measured at 12 weeks, of which 433 pregnant women were re-evaluated around 20 weeks. At both occasions, blood pressures were significantly higher in hypertensive than in normotensive pregnancies (p<0.0001). Analysis showed for DBP in standing position at cut off 79 mmHg a sensitivity, specificity, positive predictive value and negative predictive value of 72%, 64%, 15,5% and 96% at 12 weeks and 86%, 69%, 20% and 98% at 20 weeks at cut off 77 mm Hg. At 20 weeks, Area under the Curve (AUC) for DBP was 83% in standing position and 80% in supine position. For routine versus standardized blood pressure measurement, AUC was 66% versus 72% at 12 weeks and 69% versus 82% at 20 weeks, respectively. Conclusion: Simple blood pressure measurements with gestation-specific thresholds can easily be used worldwide towards improved planning of prenatal care as compared to current protocols.