Noninvasive ultrasound assessment of maternal vascular reactivity during pregnancy: a longitudinal study.

Abstract

To estimate the pattern of maternal vascular reactivity in normal and high-risk pregnancies using postocclusion brachial artery diameter. Prospective, longitudinal study of 44 low-risk singleton pregnancies and 28 high-risk pregnancies, defined as pregestational diabetes (n = 7), chronic hypertension (n = 4), twin gestation (n = 6), and a previous history of preeclampsia, fetal growth restriction, or vascular disease (n = 11). During each trimester, the brachial artery was ultrasonographically imaged above the antecubital crease. Brachial artery diameter was measured and then occluded for 5 minutes using an inflated blood pressure cuff. Changes in brachial artery diameter at 1 minute after occlusion were expressed as percent change from baseline and were compared across trimesters for both low-risk and high-risk groups, adjusting for potential confounders. Brachial artery diameters were increased after occlusion in every trimester for all groups. For low-risk women, the degree of postocclusion brachial artery dilatation was similar in the first and second trimesters, but was lower in the third trimester. In the first trimester, low-risk women had significantly greater brachial artery diameter increases at 1 minute compared with high-risk singleton pregnancies (19% compared with 12%; P <.001). Compared with low-risk women, pregnancies complicated by pregestational diabetes or chronic hypertension had significantly smaller 1-minute brachial artery diameter changes in the first trimester (7.0 +/- 0.5%, P <.001), whereas twin gestations had greater brachial artery responses (22.9 +/- 6.0%, P <.001). Women with previous preeclampsia or vascular disease had responses similar to low-risk women. Maternal vascular reactivity as assessed by postocclusion brachial artery dilatation decreases in the third trimester in both low-risk and high-risk women. In addition, singleton pregnancies at high risk for preeclampsia display decreased brachial artery reactivity compared with low-risk women.