A longitudinal investigation of the influence of psychological factors on nausea and vomiting in early pregnancy.

The purpose of this study was to elucidate psychological factors that may influence nausea and vomiting during pregnancy (NVP) progression in early pregnancy based on longitudinal observations. Fifty-nine pregnant women completed the Rhodes Index of Nausea, Vomiting, and Retching (RINVR) and General Health Questionnaire-28 (GHQ-28), and recorded their resting heart rate with photoplethysmography for 5 min to determine heart rate variability (HRV) indexes at 7-9 weeks and 11-13 weeks of gestation with a 4-week interval. GHQ-28 scores (total and subclasses) and HRV indexes at 7-9 weeks were compared among groups classified according to the presence of severe NVP (RINVR ≥ 9 points) at the two measurement points. Among women without severe NVP at 7-9 weeks, women who developed severe NVP at 11-13 weeks had significantly higher levels of anxiety/insomnia in the GHQ-28 subclasses (p = 0.018). The cross-lagged relationship from anxiety/insomnia at 7-9 weeks to RINVR at 11-13 weeks was significant (β = 0.367, p < 0.001). Among women with severe NVP at 7-9 weeks, women whose severe symptoms subsided at 11-13 weeks had significantly higher high-frequency (HF) power (p = 0.010), and women with relatively higher HF power demonstrated a significant reduction in RINVR (interaction effect, p = 0.035). During early pregnancy, women with strong anxiety/insomnia symptoms tend to have NVP symptoms that become more severe as the pregnancy progresses. The higher HF power in women whose severe NVP subsided within 4 weeks suggests a contribution of emotion regulation to early amelioration of NVP.