Table I.
Age-standardized characteristics of participants in the Nurses’ Health Study II population at cohort baseline, in 1989, by reported frequency of tanning bed use.
| During high school/college |
Tanning bed use between ages 25 and 35 |
||||||||
|---|---|---|---|---|---|---|---|---|---|
| None (n = 61 923) | 1–2 times/year (n = 2956) | 3–5 times/year (n = 1477) | >6 times/year (n = 2048) | None (n = 54853) |
1–2 times/year (n = 5463) | 3–5 times/year (n = 2900) | >6 times/year (n = 5193) | ||
| Age (years)a,b | 34.95 (4.54) | 32.94 (4.88) | 32.44 (4.96) | 31.76 (4.81) | 35.17 (4.53) | 33.33 (4.60) | 32.80 (4.53) | 32.33 (4.46) | |
| Age at menarche | |||||||||
| <11, % | 24 | 21 | 22 | 23 | 24 | 23 | 21 | 24 | |
| 12–13, % | 58 | 59 | 59 | 57 | 58 | 58 | 59 | 57 | |
| 14+, % | 18 | 20 | 19 | 20 | 18 | 19 | 19 | 19 | |
| Menstrual cycle length at ages 18–22 | |||||||||
| <25 days, % | 10 | 10 | 13 | 12 | 10 | 12 | 14 | 14 | |
| 26–31 days, % | 66 | 67 | 66 | 67 | 66 | 68 | 66 | 67 | |
| 32–39 days, % | 16 | 16 | 15 | 13 | 16 | 13 | 14 | 12 | |
| 40+ days, % | 8 | 7 | 6 | 8 | 8 | 7 | 7 | 7 | |
| Parous, % | 71 | 66 | 63 | 63 | 72 | 64 | 62 | 65 | |
| Current oral contraceptive use % | 13 | 15 | 16 | 18 | 12 | 16 | 18 | 19 | |
| History of infertility, % | 16 | 15 | 16 | 16 | 16 | 16 | 16 | 15 | |
| BMI at age 18a, kg/m2 | 21.27 (3.26) | 21.02 (3.02) | 20.93 (2.84) | 20.96 (3.25) | 21.27 (3.24) | 21.00 (3.11) | 21.18 (3.29) | 21.18 (3.39) | |
| Current BMIa, kg/m2 | 23.91 (4.90) | 23.36 (4.62) | 23.33 (4.39) | 23.36 (4.36) | 23.96 (4.95) | 23.29 (4.35) | 23.51 (4.48) | 23.48 (4.56) | |
| Natural hair colour | |||||||||
| Black, % | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | |
| Dark brown, % | 39 | 37 | 39 | 37 | 39 | 37 | 37 | 36 | |
| Light brown, % | 40 | 41 | 37 | 41 | 39 | 40 | 40 | 42 | |
| Blonde, % | 16 | 18 | 18 | 18 | 16 | 17 | 19 | 18 | |
| Red, % | 4 | 3 | 4 | 3 | 4 | 3 | 3 | 3 | |
| Moles on leg | |||||||||
| None, % | 49 | 47 | 46 | 44 | 50 | 48 | 48 | 46 | |
| 1–2 moles, % | 19 | 19 | 20 | 19 | 19 | 18 | 19 | 20 | |
| 3–4 moles, % | 10 | 10 | 11 | 11 | 10 | 11 | 11 | 11 | |
| 5–9 moles, % | 7 | 7 | 8 | 7 | 7 | 7 | 8 | 7 | |
| 10+ moles, % | 15 | 17 | 16 | 19 | 15 | 16 | 15 | 17 | |
| Current smoker, % | 12 | 13 | 14 | 14 | 11 | 14 | 15 | 18 | |
| Predicted vitamin D scorea,c | 31.25 (3.46) | 31.69 (3.41) | 31.91 (3.35) | 31.91 (3.29) | 31.20 (3.46) | 31.81 (3.32) | 31.94 (3.36) | 31.71 (3.38) | |
| Annual income | |||||||||
| <$75 000, % | 43 | 40 | 39 | 39 | 43 | 40 | 42 | 44 | |
| $75 000 to $99 999, % | 21 | 22 | 21 | 23 | 22 | 20 | 21 | 22 | |
| >$100 000, % | 35 | 38 | 40 | 38 | 35 | 40 | 37 | 35 | |
| Subjective social status | |||||||||
| High, % | 39 | 41 | 38 | 40 | 39 | 39 | 40 | 38 | |
| Medium, % | 23 | 23 | 26 | 22 | 23 | 23 | 22 | 22 | |
| Low, % | 38 | 36 | 36 | 38 | 38 | 38 | 38 | 40 | |
Values of polytomous variables may not sum to 100% due to rounding.
a
Mean (SD).
b
Value is not age adjusted.
c
From 1991 questionnaire.