Stress during pregnancy: Is the autonomic nervous system influenced by anxiety?

The goal of this study was to investigate whether anxiety during pregnancy can be linked with the autonomic nervous system (ANS) via different heart rate variability (HRV) parameters. More than 100 pregnant women were included and underwent 24h ECG monitoring including a stress test and the state trait anxiety inventory (STAI) questionnaire, dividing them in a low, medium or high anxiety group. Standard time and frequency domain and nonlinear HRV parameters were calculated to describe self-similarity, complexity and chaotic signatures. Almost all HRV parameters were negatively correlated with the anxiety level, though not statistically significant, except the chaos level. Positive correlations were found for detrended fluctuation analysis and sympathetic activity parameters. Most of the significant between-group differences were found between the low and medium anxiety groups. To conclude, the ANS modulation is slightly influenced by the anxiety level, but not as strongly as hypothesized before.