Skip to main content

Table 1 Age and age-standardized characteristics at urine collection (1996–1999) of 1,343 women across quartiles of urinary aMT6s (ng/mg creatinine) in Nurses’ Health Study II a

From: The association of body size in early to mid-life with adult urinary 6-sulfatoxymelatonin levels among night shift health care workers

Characteristics Quartiles of urinary aMT6s levels
Q1 (lowest) Q2 Q3 Q4 (highest)
N 335 336 336 336
Urinary aMT6s (ng/mg creatinine)b,c 20.4 (9.2-27.6) 37.0 (30.6-43.0) 53.0 (46.3-61.3) 84.4 (67.6-124.2)
Age (years)c 44.3 (4.5) 44.0 (4.2) 43.2 (4.4) 43.6 (4.1)
Birth weight, ≥ 7 lbs, % 64 62 59 63
Somatotype at age 5, ≥ diagram 5, % 7 7 8 5
Somatotype at age 10, ≥ diagram 5, % 11 10 10 10
Height (inches) 65.1 (2.6) 64.8 (2.5) 64.8 (2.6) 64.8 (2.4)
Body mass index at age 18 (kg/m2) 21.2 (2.9) 20.8 (2.5) 20.8 (2.9) 20.5 (2.3)
Current body mass index (kg/m2) 26.3 (6.0) 24.6 (4.7) 24.4 (4.5) 23.6 (4.0)
Weight change since age 18, ≥ 20 kg, % 26 17 17 11
Waist circumference (inches) 31.3 (5.0) 30.3 (4.2) 30.0 (4.5) 29.3 (3.6)
Waist to hip ratio 0.8 (0.1) 0.8 (0.1) 0.8 (0.1) 0.8 (0.1)
First morning urine sample, % 89 94 96 98
Full-term pregnancies, % 95 91 93 93
Physical activity (METs/week)d 19.6 (25.0) 20.3 (22.8) 20.5 (23.5) 20.0 (29.6)
Alcohol intake (g/day) 3.7 (6.2) 3.7 (6.7) 3.2 (5.6) 3.9 (8.2)
Pack-years of cigarette smoking 13.6 (11.8) 10.3 (8.3) 12.1 (11.1) 11.9 (10.3)
Current smoker, % 8 6 3 6
Nulliparous, % 18 18 18 20
Post-menopausal, % 11 8 6 9
Current post-menopausal hormone use, % 8 7 5 8
Ever oral contraceptive use, % 86 86 84 85
Current antidepressant use, % 10 14 14 12
Ever night shift work in 2 weeks prior to urine collection, % 9 11 7 7
Ever night shift work in 2 years prior to urine collection, % 15 14 14 10
Ever night shift work prior to urine collection, % 67 66 72 62
  1. Values are means (SD) or percentages and are standardized to the age distribution of the study population unless otherwise noted.
  2. aaMT6s, 6-sulfatoxymelatonin.
  3. bValues are medians (10th-90th percentile).
  4. cValue is not age adjusted.
  5. dMetabolic equivalents from recreational and leisure time activities.