Deep and slow breathing increases vagal modulation in pregnant women

Ana Claudia Silva Farche, Soraia Jurgensen, Paulo Giusti Rossi, Anielle Cristhine M. Takahashi, Audrey Borghi-Silva


AIMS: To compare the responses of the heart rate autonomic modulation in pregnant and non-pregnant women before and after the respiratory sinus arrhythmia maneuver.

METHODS: A cross-sectional study was conducted with a sample of 24 women, divided into two groups: pregnant group (independent of gestational age) and control group (non-pregnant). The evaluation consisted of recording the RR intervals using a cardiofrequencimeter, for analysis of linear and nonlinear indices of heart rate variability. The evaluations were made at rest in left lateral decubitus, before and after the maneuver of accentuation of respiratory sinus arrhythmia, consisting of slow breaths five to six cycles per minute. The expiration/inspiration ratio and the difference between inspiration and expiration were evaluated during the maneuver. Results were compared between the two groups (pregnant and non-pregnant), as well as those obtained in each group before and after the maneuver. For the statistical analysis the level of significance considered was p <0.05.

 RESULTS: Linear indices showed increased baseline sympathetic modulation (low frequency band) in pregnant women when compared to non-pregnant women (pregnant women: 68.9±28.1; non pregnant women: 49.3±11.7; p=0,002). After the respiratory maneuver, the root mean square of successive differences in the RR intervals index increased in the pregnant group (pre-maneuver: 34.5±5.7; post-maneuver: 38.9±5.8; p=0,002) indicating an increase in the parasympathetic system for this population after the maneuver. In addition, there was an increase in the complexity values after the maneuver, suggested by the Shanon entropy for both groups, being the increase higher in the pregnant women. Regarding the indices evaluated during the respiratory sinus arrhythmia maneuver, both groups presented expiration/inspiration ratio values greater than 1, which suggests integrity of the autonomic nervous system.

CONCLUSIONS: There was an improvement in the regulation of the autonomic nervous system after the respiratory maneuver for pregnant women, suggesting that the slow and deep breathing pattern may increase vagal modulation and confer a cardioprotective effect, besides causing relaxation and a sense of well-being.


pregnancy; respiration; cardiovascular system; heart rate; respiratory sinus arrhythmia; autonomic nervous system.


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