Slow deep breathing (SDB) has a therapeutic effect on autonomic tone. Our previous studies suggested that coupling of the cardiovascular to the respiratory system mediates plasticity expressed in sympathetic nerve activity. We hypothesized that SDB evokes short-term plasticity of cardiorespiratory coupling (CRC). We analyzed respiratory frequency (fr), heart rate and its variability (HR&HRV), the power spectral density (PSD) of blood pressure (BP) and the ventilatory pattern before, during, and after a 20-min epoch of SDB. During SDB, CRC and the relative PSD of BP at fr increased; mean arterial pressure decreased; but HR varied; increasing (n=3), or decreasing (n=2) or remaining the same (n=5). After SDB, short-term plasticity was not apparent for the group but for individuals differences existed between baseline and recovery periods. We conclude that a repeated practice, like pranayama, may strengthen CRC and evoke short-term plasticity effectively in a subset of individuals.

INTRODUCTION:Women of color in the United States have an increased risk of maternal morbidity and a higher risk of cesarean delivery (CD) compared to White women. This study aims to determine whether maternal race/ethnicity influenced mode of delivery (MOD) of twin gestations.METHODS:This was an IRB-approved, retrospective cohort study of all twin deliveries at a single institution between 1/1/2001 and 12/31/2018. Pregnancies delivered<24 weeks or with intrauterine fetal demise were excluded. The primary exposure, self-reported race/ethnicity, was categorized into five groups: White, Hispanic, non-Hispanic Black, Asian/Pacific Islander (PI)/Alaska Native (AN), and Other/Mixed. The primary outcome was CD. Statistical analyses included univariate analysis via Chi-square and ANOVA and logistic regression analysis.RESULTS:A total of 796 pregnancies were included; 377 (47.8%) of participants identified as White, 236 (29.9%) as Hispanic, 83 (10.5%) as Asian/PI/AN, 44 (5.6%) as Black, and 50 (6.3%) as Other/Mixed. BMI, maternal age at delivery, chorionicity, and parity were different by race/ethnicity groups, but gestational age at delivery was not. The overall rate of CD was 71.1% and did not vary by race/ethnicity (P=.51). There were no differences by race/ethnicity when analysis was limited to those delivering>34 weeks and birthweights>2,500 g (P=.07) or among only nulliparous women (P=.77). In multivariable analysis, only nulliparity was associated with increased risk of CD (P<.01).CONCLUSION:Rate of CD for twin gestations is high but was not related to maternal race/ethnicity in this cohort. Further study is needed to evaluate the indications for cesarean deliveries across racial/ethnic groups in twin gestations as this was not examined in this cohort.

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