The pulse wave analysis of normal pregnancy: investigating the gestational effects on photoplethysmographic signals

Normal pregnancy is associated with profound alterations in the maternal cardiovascular system and PPG represents a sensitive and convenient technique capable of tracking changes in the pulsatile function of arteries. The aim of this study was to investigate the effects of maternal cardiovascular alterations on the finger tip photoplethysmography (PPG) during normal gestation.

Thirty five healthy pregnant women were studied at each trimester of pregnancy and again on gestational age using PPG signals, peripheral blood pressure (BP) and heart rate (HR).

Comparing with nonpregnant controls, several characteristic differences in PPG derived parameters and morphologies occurred in the pregnant. PAI, RI, PTT as well as AUC1 and Y1 of bcAUC1 were different and significant difference had been found in second and third trimester, despite little change in the peripheral blood pressure. The mean heart rate increased linearly with gestational age.

This study has confirmed that normal pregnancy is associated with profound alterations in PPG signals occurred principally as a result of maternal cardiovascular adaptation and PPG-based noninvasive assessment of cardiovascular activities is feasible throughout pregnancy. Using this technique we demonstrated a delay in wave reflection within the arterial tree and a reduction in magnitude of arterial wave reflections in normal pregnancy which is consistent with previous observations and the known cardiovascular changes of pregnancy.