[Maternal Endothelial Function in the Course of Pregnancy and Postpartum - Ultrasound-Based Longitudinal Assessment Using Flow-Mediated Dilatation (FMD).]
ABSTRACT PURPOSE: NO-triggered vasodilatation decreases peripheral vascular resistance in pregnancy. Using a noninvasive ultrasound technique, flow-mediated vasodilatation can be quantified. We used this technique to detect changes in endothelial function during pregnancy and postpartum. MATERIALS AND METHODS: In a prospective longitudinal study 16 healthy pregnant women were assessed for flow-mediated dilatation of the brachial artery during pregnancy (first trimester T 1 < 14th gestational week, second trimester T 2 ≥ 14th - 27th gestational week, third trimester T 3 ≥ 28th gestational week) and postpartum (> 6 weeks postpartum). As a control group, flow-mediated dilatation was determined in 19 healthy non-pregnant women. RESULTS: Flow-mediated dilatation (%) increased significantly in normal human pregnancy from the first trimester (T1 8.0 ± 5.58 vs. T 2 15.2 ± 5.19, p < 0.003) to the second trimester and reached its maximum in mid-trimester. Towards the end of pregnancy, flow-mediated dilatation decreased significantly (T2 vs. T 3 9.15 ± 3.61, p < 0.004). Mean values of flow-mediated dilatation are significantly higher during the second and third trimester of pregnancy compared to non-pregnant controls (T2 vs. NP 6.17 ± 4.39, p < 0.001; T 3 vs. NP, p < 0.047). Postpartum flow-mediated dilatation decreased to values of early pregnancy. CONCLUSION: During pregnancy maternal endothelial function shows an increase in flow-mediated dilatation and then reverts postpartum. Using ultrasound-based measurement of flow-mediated dilatation, these physiological changes in pregnancy can be reliably detected.