A reappraisal of second trimester mean arterial pressure as a predictor of pregnancy induced hypertension

Early prediction of preeclampsia

Effective screening for the development of early onset preeclampsia (PE) can be provided in the first-trimester of pregnancy. Screening by a combination of maternal risk factors, uterine artery Doppler, mean arterial pressure, maternal serum pregnancy-associated plasma protein-A, and placental growth factor can identify about 95% of cases of early onset PE for a false-positive rate of 10%.

Hypertensive disorders in pregnancy: screening by systolic diastolic and mean arterial pressure at 11-13 weeks

OBJECTIVES

To examine the performance of screening for hypertensive disorders in pregnancy and to compare systolic blood pressure (BP), diastolic BP, and mean arterial pressure (MAP) measured by validated automated devices in a large population of pregnant women at 11-13 weeks.

METHODS

We recorded maternal variables and measured BP by automated devices in 9149 women with singleton pregnancies. The performance of screening for preeclampsia (PE) and gestational hypertension (GH) by combinations of disease-specific maternal factor-derived a priori risk with systolic BP, diastolic BP, and MAP was determined.

RESULTS

There were 8061 cases that were unaffected by PE or GH, 37 that developed PE requiring delivery before 34 weeks (early-PE), 128 with late-PE, and 140 with GH. The systolic BP, diastolic BP, and MAP were significantly higher in early-PE, late-PE, and GH than in the controls (p < 0.0001). The systolic BP was significantly higher in early-PE than in late-PE (p = 0.008) and both systolic BP and MAP were significantly higher in early-PE than in GH (p < 0.01). The best performance in screening was provided by MAP. The detection rate of early-PE at a 10% false-positive rate increased from 47% in screening by maternal factor-derived a priori risk alone to 76% in screening by its combination with MAP. The respective detection rates for late-PE increased from 41 to 52% and for GH increased from 31 to 48%.

CONCLUSION

The measurement of BP can be combined with the maternal factor-derived a priori risk to provide effective first-trimester screening for PE and GH.

Calcium and low-dose aspirin prophylaxis in women at high risk of pregnancy-induced hypertension

OBJECTIVE

The objectives of the study were to confirm the validity of using oscillometric measurement of MAP in the left lateral position to identify those at high risk for developing pregnancy-induced hypertension (PIH), and to assess and compare the efficacy of prophylaxis with low-dose aspirin or calcium supplementation in high-risk patients.

STUDY DESIGN

A prospective study in pregnancy; 500 normotensive, primigravid Chinese women were recruited in the second trimester of pregnancy on the basis of 80 mm Hg > or = MAP < 106 mm Hg in the antenatal clinic. They were then screened by Dinamap in a research setting, measuring MAP in the left lateral position after rest and using a cutoff value of 60 mm Hg for inclusion in the randomized study. Randomization was divided into three groups: control, low-dose aspirin, and calcium supplementation. After delivery, patients were classified as either having remained normotensive or having developed PIH, with or without proteinuria.

RESULTS

The incidence of both proteinuric and nonproteinuric PIH was significantly lower in patients screened out as low risk than in those selected as high risk using a critical value of 60 mm Hg for left lateral MAP (p < 0.05). The incidence of proteinuric PIH was significantly lower in patients given low-dose aspirin than in the control group (p < 0.05). However, the confidence intervals for the effect were wide, comparable with aspirin having no effect or leading to a 16-fold reduction in the risk of preeclampsia. For those given calcium supplementation, the reduction was not significant. There was no significant difference in the incidence of nonproteinuric PIH between the control group and the two groups receiving prophylaxis.

CONCLUSION

Oscillometric measurement of second-trimester left lateral MAP is a valid predictor of proteinuric PIH. Low-dose aspirin may offer a degree of protection from proteinuric PIH in these high-risk women. Calcium supplementation was not shown to significantly reduce the incidence of PIH.