Selected characteristics of Polish nurses and midwives: a cross-sectional study
| Characteristic | Rotating nights, (n=354) | Day shifts, (n=370) | p diff |
| Mean age (years), mean (SD) | 48.3 (5.2) | 50.2 (5.3) | 0.000 |
| Menopausal status (%) | |||
| Premenopausal | 65 | 52 | 0.000 |
| Postmenopausal | 35 | 48 | |
| Age at menopause (in postmenopausal women) (years), mean (SD) | 48.5 (3.9) | 49.6 (4.0) | 0.009 |
| Mean age at menarche (years)†, mean (SD) | 13.3 (1.4) | 13.1 (1.6) | 0.030 |
| Age at first full-term birth (≥37 weeks) (years) (%) | |||
| ≤24 | 56 | 56 | 0.426 |
| >24 to <30 | 32 | 35 | |
| ≥30 | 12 | 9 | |
| Number of full-term births (%) | |||
| 0 | 12 | 13 | 0.040 |
| 1 | 31 | 35 | |
| 2 | 49 | 49 | |
| 3–4 | 8 | 3 | |
| Body mass index (kg/m2) (%) | |||
| <25 | 35 | 38 | 0.504 |
| 25–30 | 40 | 40 | |
| >30 | 25 | 22 | |
| Smoking (%) | |||
| Current | 35 | 26 | 0.019 |
| Past | 23 | 31 | |
| Non-smoker | 42 | 43 | |
| Tea consumption (%) | |||
| Non-drinker | 12 | 14 | 0.855 |
| Infrequent | 13 | 12 | |
| Frequent | 75 | 74 | |
| Coffee consumption (%) | |||
| Non-drinker | 11 | 17 | 0.008 |
| Infrequent | 8 | 13 | |
| Frequent | 81 | 70 | |
| Physical activity (MET* hours per week), mean (SD) | 242 (78.4) | 202 (87.9) | 0.000 |
| Chronotype† (%) | |||
| Morning type | 51 | 53 | 0.326 |
| Evening type | 49 | 46 | |
| Quality of sleep PSQI (score), mean (SD) | 6.4 (3.0) | 6.9 (3.6) | 0.002 |
| Current oral contraceptives or sex hormones use (%) | |||
| Yes | 5 | 4 | 0.513 |
| No | 95 | 96 | |
| Drugs use grouped: β-blockers, non-steroid anti-inflammatory drugs, diuretics, antidepressives (%) | |||
| Yes | 17 | 20 | 0.387 |
| No | 83 | 80 | |
| Season when urine sample collected (%) | |||
| March–September | 60 | 50 | 0.008 |
| October–February | 40 | 50 | |
| Alcohol consumption the day before sample collection† (%) | |||
| Yes | 3 | 19 | 0.000 |
| No | 97 | 81 | |
| MT6s concentrations in morning urine (ng/mg cr) | |||
| Arithmetic mean, mean (SD) | 50.2 (1.7) | 50.9 (1.9) | 0.978 |
| Geometric mean, mean (SD) | 39.9 (2.2) | 39.7 (2.1) | 0.752 |
| Minimum | 0 | 3.7 | |
| Maximum | 174 | 242.9 | |
↵* Missing age at menarche for four women (two, rotating night shifts; two, day shift); chronotype (two, day shift); data on previous day alcohol drinking for four women (one, rotating night shift; three, day shift).