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Cardiovascular autonomic reflexes in mid-pregnancy
E M Ekholm1, S J Piha, K J Antila
1Department of Obstetrics and Gynaecology, Turku University, Finland.
British Journal of Obstetrics and Gynaecology
|February 1, 1993
Summary
Pregnancy blunts cardiovascular autonomic responses, including heart rate variability and reactions to the Valsalva maneuver. This indicates reduced parasympathetic control during mid-pregnancy.
Area of Science:
- Physiology
- Cardiovascular Autonomic Function
- Reproductive Medicine
Background:
- Autonomic nervous system (ANS) regulation of cardiovascular function is crucial.
- Pregnancy involves significant physiological adaptations, potentially affecting ANS control.
- Understanding these changes is vital for maternal and fetal health.
Purpose of the Study:
- To investigate physiological responses to noninvasive cardiovascular autonomic function tests in normal pregnancy.
- To compare autonomic responses between pregnant and nonpregnant women.
Main Methods:
- Sixty pregnant women (22-29 weeks gestation) and 62 nonpregnant women underwent autonomic function testing.
- Tests included Valsalva maneuver, orthostatic, quiet breathing, deep breathing, and isometric handgrip tests.
Main Results:
- Pregnant women exhibited significantly lower heart rate variability during normal breathing compared to nonpregnant controls.
- A blunted tachycardic reaction to the Valsalva maneuver was observed in pregnant women.
- The vagally mediated biphasic heart rate response to standing was attenuated in the pregnant group.
Conclusions:
- Cardiovascular autonomic responses are diminished in mid-pregnancy.
- This suggests a decrease in parasympathetic cardiovascular control during pregnancy.
- These findings highlight physiological adaptations in autonomic function during gestation.