Heart rate variability in normal and complicated pregnancies

The sympathetic division (SD) of the autonomic nervous system (ANS) was assessed by 23 tachometric parameters in 176 pregnant women using a Valenta medical diagnostic system. The activity of the ANS SD was shown to increase in the first trimester of pregnancy, progressively rise during the second and third trimesters, and decrease immediately before delivery. This is considered as a mechanism of adaptation to pregnancy. The activity of the ANS SD in pregnant women remained unchanged in mild gestosis; increased in moderate gestosis; and decreased in chronic hypertension, hypertensive circulatory disorders, and threatened preterm delivery. The role of the activity of the ANS SD in normal pregnancy and in obstetric complications is discussed.