Objectives: Radon is a major feature of radioactive springs. According to an official notification article in Japan, bathing in radioactive springs may alleviate the effects of hyperuricemia (gout), rheumatoid arthritis, and ankylosing spondylitis. This study focuses on changes in the body during the use of a low-temperature sauna at a radioactive hot spring.Methods: In this study, we measured the core temperature, skin temperature, and skin blood flow, and performed an emotional assessment (Mood Check List-Short form.2 (MCL-S.2), Visual Analog Scale (VAS), and Numerical Rating Scale (NRS)) in individuals using a sauna at a radioactive spring. Eight healthy adults participated in this study. All participants partook in two sauna interventions, including one sauna with a high radon concentration (approximately 710 Bq/m3) and one with a low radon concentration (approximately 140 Bq/m3). The indoor temperature and relative humidity of the sauna room were approximately 38°C and 78%, respectively. All participants remained in the sauna room for 40 min, and then rested in an antechamber for 40 min.Results and Discussion: Comparing the MCL-S.2 scores, a significant increase was observed in the pleasantness score in the radon intervention. In addition, after comparing the VAS scores, significant improvements in the feelings of coldness and stress were observed only in the radon intervention. Moreover, skin blood flow increased for a longer duration in the radon sauna intervention than the control intervention. The results suggest that using radon saunas gives rise to positive effects, including reducing coldness, feelings of stress, and promoting blood circulation.

Objectives  High gestational weight gain (GWG) is associated with perinatal risks to mother and child. Research shows that non-Japanese Asian women have higher GWG than Japanese women. However, no studies have compared GWG in these two populations using GWG recommendations in accordance with Japanese and Institute of Medicine (IOM) guidelines. The study aim was to compare GWG in non-Japanese Asian and Japanese pregnant women.Methods  This was a retrospective observational study. All participants were aged ≥20 years and gave birth between September 2019 and the end of October 2020 at one perinatal medical center in Japan. Medical record data were analyzed for 170 non-Japanese Asian and 316 Japanese pregnant women. We used t-tests and chi-square tests to examine differences in age, parity, smoking status, antenatal checkups, pre-pregnancy body mass index, and GWG. Logistic regression analysis was used to estimate odds ratios (95% confidence intervals) for above- and below-recommended GWG by non-Japanese Asian and Japanese status. We also analyzed differences in delivery type, abnormal blood loss, and birth size according to GWG.Results  After adjustment for confounding factors, the multivariable-adjusted OR and 95% CI for GWG above the Japanese guidelines recommendations was 1.86 (1.23-2.81) and that for GWG above IOM guidelines recommendations was 2.46 (1.45-4.16) for non-Japanese Asian women, as compared with Japanese women. Conversely, the multivariable-adjusted OR and 95% CI for GWG below Japanese guidelines recommendations was 1.55 (1.03-2.32) and that for GWG below IOM guidelines recommendations was 1.87 (1.26-2.76) for Japanese women, compared with non-Japanese Asian women. Conclusion  Because Japanese women tend to be below recommended GWG and non-Japanese Asian women tend to be above recommended GWG, midwives need to provide careful guidance to reduce perinatal risks.