Pain in labor assessed from two discomfort aspects: Physical pain intensity and psychological stress state

Aim To assess two discomfort aspects of pain in labor, physical pain intensity and psychological stress state, we analyzed the association between the two parameters. Methods Twenty‐nine pregnant Japanese women with a singleton in 37–40 weeks of gestation were analyzed. Physical pain intensity was examined by the Numeric Rating Scale (NRS). Psychological stress state was measured by chromogranin A (CgA) in saliva. Data were collected thrice during labor (at 4–6 cm and 10 cm of cervical dilatation and immediately after delivery) and were accumulated from 4–6 cm and 10 cm of cervical dilatation. The study was approved by the Ethics Committees of Osaka University and Tokyo Women's Medical University. Results The median NRS score (10, IQR = 10–18) and the median CgA in saliva (8.0, IQR = 4.3–12.0) pmol/mg at 10 cm of cervical dilatation were significantly higher than those at the other two time points (P < 0.05). Although there were no correlations between NRS scores and concentrations of CgA in saliva at the three time points, there was a significant correlation between accumulated NRS and accumulated CgA in saliva (r = 0.68, P = 0.000). There was a significant difference in the accumulated NRS scores (P = 0.005) but not in the accumulated concentrations of CgA between primiparae and multiparae. Conclusion Women in labor perceived severe pain and psychological stress with similar patterns during labor. However, these parameters were independent and need to be measured to evaluate these two discomfort aspects.