Key result
Compared to non-pregnant controls, women in their third trimester of pregnancy had significantly lower resting cardiovagal baroreflex gain (17.9 vs 24.8 ms/mmHg) and heart rate variability.
Why the study?
Does pregnancy alter cardiovagal baroreflex gain and heart rate variability at rest, during exercise, and during active recovery compared to non-pregnant states?
Observational (n=38)
No
Does pregnancy alter cardiovagal baroreflex gain and heart rate variability at rest, during exercise, and during active recovery compared to non-pregnant states?
Absolute Event Rate: 17.9% vs 24.8%
p-value: p=0.017
Pregnancy is associated with blunted resting cardiovagal baroreflex gain and heart rate variability, but cardioautonomic responses during and following peak exercise remain comparable to those of non-pregnant women.
Blunted resting baroreflex gain in third-trimester pregnancy may not affect exercise responses; leaves open long-term cardiovascular implications.
Blood pressure regulation during pregnancy is poorly understood. Cardiovagal baroreflex gain (BRG) is an important contributor to blood pressure regulation through its influence on heart rate. Heart rate fluctuations occur in response to various physiological stimuli and can be measured using heart rate variability (HRV). It is unclear how these mechanisms operate during pregnancy, particularly with regard to exercise. We examined BRG and HRV prior to, during, and following prenatal exercise. Forty-three pregnant (n = 10 first trimester (TM1), n = 17 second trimester (TM2), n = 16 third trimester (TM3)) and 20 nonpregnant (NP) women underwent an incremental peak exercise test. Beat-by-beat blood pressure (photoplethysmography) and heart rate (lead II electrocardiogram) were measured throughout. BRG (the slope of the relationship between fluctuations in systolic blood pressure and the R-R interval) and HRV (root mean square of the successive differences; RMSSD) were assessed at rest, during steady-state exercise (EX), and during active recovery. BRG decreased with gestation and was lower in the TM3 group than in the NP group (17.9 ± 6.9 ms/mm Hg vs 24.8 ± 7.4 ms/mm Hg, p = 0.017). BRG was reduced during EX in all groups. Resting HRV (RMSSD) also decreased with gestation and was lower in the TM3 group than in the NP group (29 ± 17 ms vs 48 ± 20 ms, p < 0.001). RMSSD was blunted during EX in all groups compared with rest. During active recovery, RMSSD was further blunted compared with EX in the NP group but not during pregnancy (TM1, TM2, and TM3). Compared with the nonpregnant controls, the pregnant women had lower BRG and HRV at rest, but comparable cardioautonomic control during both exercise and active recovery following peak exercise.
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Purdy et al. (2018) conducted an observational in Pregnancy (n=38). Incremental peak exercise test vs. Non-pregnant women was evaluated on Resting cardiovagal baroreflex gain (BRG) (p=0.017). Compared to non-pregnant controls, women in their third trimester of pregnancy had significantly lower resting cardiovagal baroreflex gain (17.9 vs 24.8 ms/mmHg) and heart rate variability.
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