It has been suggested that shift work, night work in particular, affects worker's psychophysical health. However, the effects of night work on the health of pregnant women are not physiologically well elucidated. The effects of night work on the biological function of pregnant women were studied in the present study. Three pregnant and six non-pregnant nurses that engaged in fastrotating shift system cooperated for the study. The 24-h urine samples were collected in two time frames, daytime (07:00 to 23:00) and nighttime (23:00 to 07:00) on the day shift, the night shift and the days off. Urinary concentrations of 6-sulfatoxymelatonin and norepinephrine were measured by enzyme-linked immunosorbent assay and estriol by radioimmunoassay. The excretion profiles of urinary 6-sulfatoxymelatonin in the pregnant and the non-pregnant women were altered on the night shift, which might relate the derangement of circadian rhythm of melatonin secretion. The urinary norepinephrine level during the night work was considerably higher in the pregnant women, which indicated the presence of higher physical burden in them due to the night work. The urinary estriol level was not significantly affected by shift, day/night and individual factors, and the effect of night work on urinary estriol level of the pregnant women remained uncertain. The results of the present study suggested that the night work of the pregnant shift workers should be much more relieved.

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We investigated the parasympathetic nervous response to psychological test using heart rate variation (HRV) during deep breathing in elderly patients with hand-arm vibration syndrome and healthy controls. Average age (SD) of 16 patients with vibration-induced white finger (VWF), 13 patients without VWF and 12 healthy controls was 60.1 (2.8), 60.6 (4.2) and 58.8 (3.8), respectively. After an initial supine rest for 40 min, psychological test (Stroop color word test and mirror drawing test) was performed for 20 min. The indexes of HRV (Mean R-R, SD, RMSSD and CV) were calculated. Blood pressure and heart rate were also measured. The indexes of HRV did not differ between the groups before exposure. The SD, RMSSD and CV of the patients without VWF during supine deep breathing after 3 min post-exposure supine rest were significantly lower than those of the control group (p<0.05). The Mean R-R of the patients without VWF significantly increased (p<0.05). Blood pressure did not differ in either before or after exposure measurements. The results suggest that the post-exposure response of the parasympathetic nervous system to psychological test reduced in the patients without VWF. Key words:Hand-arm vibration syndrome, Psychological test, Parasympathetic responseVibration-induced white finger, Heart rate variation, It has been suggested that exposure to hand-arm vibration might affect autonomic nervous functions and has been demonstrated on the basis of subjective symptoms complained with higher prevalence rates by patients with hand-arm vibration syndrome than healthy controls" 2).In clinical neurology the responses of cardiovascular reflexes have been used to examine the function of the autonomic nervous system3° 4). It has been accepted that respiratory sinus arrhythmia in supine deep breathing is vagally mediated, and variation of heart rate parameters due to respiratory arrhythmia is considered as an indicator of the parasympathetic nervous functions' 6)In this study, we examined a group of elderly patients with hand-arm vibration syndrome and healthy controls to *To whom correspondence should be addressed .evaluate the parasympathetic nervous activity using heart rate variation. Because the heart rate variation decreases with increasing age's, we manipulated levels of cardiac sympathetic and parasympathetic activity of the subjects exposing them to psychological test and measured R-R intervals in supine deep breathing before exposure and after 3 min post-exposure supine rest. Blood pressure and heart rate were also measured. We studied 41 male subjects. Sixteen of them with agerange 55 to 66 (60.1 ± 2.8) years, were workers exposed to vibration and experienced attacks of vibration-induced white finger during the past year (VWF(+) group), 13 with agerange 54 to 65 (60.6 ± 4.2) years, were workers exposed to vibration but did not experience attacks of vibration-induced white finger (VWF(-) group) and 12 healthy workers with age-range 51 to 61(58.8 ± 4.0) years, were examined as a