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Table 1 Characteristics of participants from the Uterine Fibroid Study included in the menstrual cycle characteristics analysis (N = 636), Washington D.C. (1996 – 1999)

From: Lower plasma 25-hydroxyvitamin D is associated with irregular menstrual cycles in a cross-sectional study

  N (%) 25(OH)D mean (SD)
25(OH)D   
 ≤20 ng/mL 484 (76) --
 >20 ng/mL 152 (24) --
Irregular cycles   
 No 588 (92) 14.3 (8.3)
 Yes 48 (8) 10.4 (6.1)
Short cycles (17 – 25 days)   
 No 453 (71) 14.7 (8.4)
 Yes 135 (29) 13.1 (7.9)
Long cycles (32 – 56 days)   
 No 566 (89) 14.3 (8.3)
 Yes 22 (11) 16.3 (9.4)
Age   
 35 - 39 310 (49) 14.4 (8.3)
 40 - 44 326 (51) 13.7 (8.1)
Race   
 White 216 (34) 20.5 (8.1)
 African-American 369 (58) 10.1 (5.8)
 Other 51 (8) 15.3 (5.7)
Education   
 Lest than a college degree 311 (49) 11.0 (6.5)
 College graduate or more 319 (50) 17.0 (8.7)
 Missing 6 (0.9)  
Body mass index   
 <25 kg/m2 258 (41) 17.6 (9.0)
 25 - < 30 170 (27) 13.7 (7.5)
 30 - <40 159 (25) 10.2 (5.7)
 ≥40 49 (8) 9.0 (4.5)
Smoker   
 Non-smoker 490 (77) 14.8 (8.4)
 Current smoker 146 (23) 11.6 (7.1)
Alcohol (drinks per week)   
 0 120 (19) 10.6 (6.1)
 >0 - 1 188 (30) 13.3 (7.4)
 >1 – 7 211 (33) 16.2 (8.5)
 >7 79 (12) 15.3 (10.0)
 Missing 40 (6)  
Vigorous physical activity   
 0 – 1.8 MET-hours/weeka 203 (32) 11.9 (7.2)
 >1.8 – 4.1 203 (32) 14.2 (8.1)
 >4.1 – 6.5 108 (17) 15.0 (8.5)
 >6.5 – 24.3 121 (19) 16.6 (8.9)
 Missing 1 (0.2)  
Age at menarche   
 <11 years 51 (8) 12.4 (7.1)
 11 - 14 506 (80) 14.3 (8.2)
 >14 years 77 (12) 13.4 (8.9)
 Missing 2 (0.3)  
  1. aMET = Metabolic equivalents.