Mean MT6s concentrations by type of night shift work during the 7 days preceding the morning urine sample collection: a cross-sectional study of Polish nurses and midwives
| Characteristic (No. of women) | Morning MT6s (ng/mg Cr), mean (95% CI) | Adjusted* morning MT6s (ng/mg Cr), mean (95% CI) |
| Night shifts during preceding week | ||
| 1 (88) | 47.9 (41.2 to 54.5) | 46.8 (41.0 to 52.7) |
| 2 (209) | 43.3 (39.2 to 47.5) | 46.2 (42.4 to 50.0) |
| >3 (57) | 46.0 (37.8 to 54.2) | 44.9 (37.7 to 52.1) |
| p | 0.587 | 0.695 |
| Night shifts hours during preceding week | ||
| ≤24 (273) | 44.7 (41.0 to 48.3) | 46.7 (43.3 to 50.0) |
| >24 (81) | 45.5 (38.7 to 52.4) | 44.5 (38.5 to 50.4) |
| p | 0.830 | 0.528 |
| Consecutive nights immediately before morning urine collection | ||
| 1 (339) | 45.2 (41.9 to 48.5) | 46.5 (43.5 to 49.5) |
| ≥2 (15) | 38.1 (23.6 to 52.6) | 38.5 (25.8 to 51.2) |
| p | 0.367 | 0.252 |
↵* Adjusted for age, evening MT6s concentration, number of full-term births and age at menarche.