Return of autonomic nervous activity after delivery: role of aortocaval compression.
We have compared measures of heart rate variability (HRV) in 15 women in late pregnancy before and 3 months after delivery and in 20 non-pregnant controls, to study the effect of aortocaval compression on autonomic nervous activity. Normalized high-frequency power was used as an index of vagal activity and the low-/high-frequency power ratio as index of sympathovagal balance. We found that the decrease in vagal activity and increase in sympathovagal balance before delivery returned to normal 3 months after delivery. Percentage changes in vagal activity and sympathovagal balance 3 months after delivery in the left lateral decubitus position were least among three recumbent positions. The relief of aortocaval compression as a result of delivery of the fetus may be the main cause of return of autonomic nervous activity 3 months after delivery. Postpartum hormonal changes may also contribute to return of autonomic nervous activity after delivery.
Chen
G Y
GY
Department of Medicine, Provincial Tao-Yuan General Hospital, Taiwan, Republic of China.
Kuo
C D
CD
Yang
M J
MJ
Lo
H M
HM
Tsai
Y S
YS
D000328:Adult; D001011:Aorta; D001341:Autonomic Nervous System / Q000503:physiopathology*; D016022:Case-Control Studies; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007024:Hypotension, Orthostatic / Q000503:physiopathology*; D010275:Parasympathetic Nervous System / Q000503:physiopathology; D049590:Postpartum Period; D011247:Pregnancy; D011248:Pregnancy Complications / Q000503:physiopathology*; D011312:Pressure; D018709:Statistics, Nonparametric; D016683:Supine Position; D013564:Sympathetic Nervous System / Q000503:physiopathology; D014684:Venae Cavae