Responsiveness of placental blood flow to hyperventilation test as predictive criterion of pregnancy outcome

The aim of the study was to develop an approach to early prediction of pregnancy complications (PC) via the evaluation of the responsiveness of placental blood flow to hyperventilation (HV) test by using the Doppler ultrasonography and measuring the maternal heart rate variability (HRV), characteristic of various types of autonomic nervous regulation in pregnant women. Doppler indices and HRV variables (spectral, nonlinear, and timedomain parameters) were studied in the umbilical and uterine arteries. A total of 88 pregnant women with PC (preeclampsia, prematurity, fetal growth retardation, and labor abnormality) and 40 healthy pregnant women of comparable age, parity, and pregestational body weight were examined. Data showed that HV test in healthy pregnancy (HP) led to increase in blood flow velocities in umbilical artery together with insignificant tendency towards an increase in maternal heart rate. In PC group, blood flow velocity dynamics in umbilical artery was negative on the average. In HP group, HV effect was associated with the increases in the very low frequency (VLF) spectral component and in the detrended fluctuation analysis (DFA) parameter of HRV. All documented changes were characteristic of the subgroup of pregnant women who initially had elevated sympathetic and/or baroreflex activity. Hyperventilation testrelated changes in umbilical artery blood flow velocities, VLF, and DFA may serve as criteria for the early prediction of complications in pregnancy.