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Table 2 Mean serum vitamin D levels in relation to reproductive history, life–style factors and season

From: Determinants of serum levels of vitamin D: a study of life-style, menopausal status, dietary intake, serum calcium, and PTH

Factor No. Mean (95% CI) T–test (p–value*) ANOVA (p–value)
Age (years)
 ≤50 162 84.4 (80.3–88.6) Ref.
 >50 – ≤55 164 88.6 (84.3–92.8) 0.10
 >55 – ≤60 141 87.7 (83.0–92.5) 0.29
 >60 – ≤65 146 88.5 (84.6–92.5) 0.13
 >65 114 93.6 (88.3–98.9) 0.01 0.107
BMI (kg/m2)
 <20 41 93.2 (83.6–102.8) 0.62
 ≥20 – <25 336 91.0 (88.1–93.9) Ref.
 ≥25 – <30 259 87.9 (84.6–91.1) 0.16
 ≥30 91 77.3 (71.7–82.9) <0.001 <0.001
Oral contraception
 No 366 86.9 (84.2–89.5) Ref.
 Yes 361 89.7 (86.8–92.6) 0.011 0.011
Menopausal status
 Pre 187 85.0 (81.1–88.8) Ref.
 Peri/Post 540 89.4 (87.1–91.7) 0.056 0.056
MHT** (n = 537)
 No 422 89.2 (86.6–91.8) Ref.
 Yes 115 90.8 (85.7–95.9) 0.57 0.27
Smoking status
 Never 306 87.9 (85.0–90.8) Ref.
 Current 201 87.3 (83.3–91.3) 0.813
 Ex 220 89.7 (86.0–93.4) 0.443 0.635
Alcohol consumption
 Zero 57 80.3 (72.8–87.8) Ref.
 <15 g/day 457 88.9 (86.4–91.4) 0.025
 15 – 30 g/day 100 89.5 (84.8–94.3) 0.032
 >30 g/day 20 82.7 (66.3–99.1) 0.762
 Infrequent 93 89.7 (83.9–95.5) 0.049 0.169
Baseline season
 Spring 199 78.6 (74.8–82.4) Ref.
 Summer 203 99.0 (95.2–102.7) <0.001
 Autumn 149 89.6 (85.8–93.5) <0.001
 Winter 176 85.7 (81.8–89.6) 0.011 <0.001
Education
 O–level college 496 89.3 (86.9–91.7) Ref.
 A–level college 57 83.4 (75.8–91.0) 0.128
 University 174 87.0 (83.0–91.0) 0.324 0.236
Socio–economic index
 Manual 274 89.0 (85.6–92.5) Ref.
 Non–manual 396 88.5 (85.9–91.1) 0.796
 Employer 56 83.9 (77.3–90.5) 0.221 0.158
Born in Sweden
 Yes 657 89.3 (87.2–91.4) Ref.
 No 70 78.6 (72.0 –85.3) 0.002 0.00
  1. * Compared to reference (p–value). ** Only in peri/postmenopausal.