Arterial stiffness and peripheral vasodilatation markers measured by digital Photoplethysmography in normal pregnancy and in those complicated by pre-eclampsia/gestational hypertension.

Background: Pre-eclampsia is a disease of pregnancy, clinically defined by the onset of hypertension and proteinuria after the 20th gestational week. The aims of the present studies were: i) to observe changes of the “Stiffness Index”(SI) and the “Reflection Index”(RI, index of periferic vasodilatation), measured by digital photoplethysmography (Pulse Tace 1000) throughout pregnancy (longitudinal study); ii) to compare these indices between normotensive pregnant women either with pregnant women at risk for pre-elampsia (R_PE) or with women who developed pre-eclampsia/gestational hypertension (PE/IPTG) in the three trimesters (cross-sectional study) iii) to explore the capacity to predict the outcomes of pregnancy by using the same photoplethysmographic markers.Methods: We recruited 357 pregnant women, 210 in the 1st trimester (64 with R_PE and 146 without known risk factors for PE); 143 in the 2nd (22 with PE/IPTG and 121 normotensive women) and 157 in the 3rd trimesters (30 with PE/IPTG and 127 normotensive women). The analysis was repeated in subgroups matched for pregravidic BMI.Result: Women followed longitudinally throughout pregnancy showed a significant fall in both photoplethysmographic indices from the 1st to the 2nd trimester (SI 7,3 -->6,5-->7,1 m/sec; RI 61,2-->51,8-->50,9% respectively in the 1st, 2nd and 3rd trimester; p<0,001), without significant variations of blood pressure (BP). In the 1st trimester BP was higher in pregnant women with risk factors than in women without risk factors, wherease the SI and RI were similar in both groups. In the 2nd trimester SI was higher in PE/IPTG in comparison with normotensive pregnant women (8,15±1,9m/s vs. 6,6±0,8m/s p<0,001). In the 3rd trimester, similarly to BP and SI, even the RI was higher in IPTG/PE pregnant women (SI 8,5±2m/s vs. 7,1±1,4m/s p<0,001; RI 59,5±11,7% vs.51,4±11,2% p=0,001). We obtained similar results even in the subgroups matched for pregravidic BMI. No haemodinamic indices, when mesured in the 1st trimester, can predict the outcomes of pregnancy. Conclusion: These results suggest that changes in arterial stiffness and periferic vasodilatation measured by digital photoplethysmography during pregnancy are similar with those measured by more complex methods. SI rise significantly in IPTG/PE women starting from the 2nd trimester, confirming the augmentation of arterial stiffness and vasocostriction in women with IPTG/PE.