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Table 2 Beta (β) and 95 % confidence interval for semen-quality parameters according to categories of serum vitamin D

From: Is there a relationship between serum vitamin D and semen parameters? A cross-sectional sample of the Iranian infertile men

  Categories of serum vitamin D
Deficient (< 10 ng/ml) Insufficient (10–20 ng/ml) Sufficient (> 20 ng/ml) P trend
Semen volume (mL)
Crude Ref 0.004 (-0.59, 0.60) 0.67 (0.10, 1.24) 0.006
Model 1 Ref -0.05 (-0.66, 0.55) 0.63 (0.05, 1.20) 0.008
Model 2 Ref -0.006 (-0.61, 0.60) 0.62 (0.04, 1.19) 0.010
Model 3 Ref 0.03 (-0.57, 0.64) 0.63 (0.06, 1.20) 0.010
Sperm count (106/mL)
Crude Ref 7.32 (-3.19, 17.85) 11.83 (1.84, 21.82) 0.021
Model 1 Ref 8.57 (-2.02, 19.16) 12.71 (2.70, 22.72) 0.015
Model 2 Ref 10.03 (-0.49, 20.56) 13.23 (3.32, 23.13) 0.013
Model 3 Ref 9.99 (-0.43, 20.42) 14.40 (4.56, 24.25) 0.005
Sperm total motility (%)
Crude Ref 13.39 (7.36, 19.43) 18.31 (12.59, 24.04) < 0.001
Model 1 Ref 13.57 (7.48, 19.66) 18.44 (12.68, 24.20) < 0.001
Model 2 Ref 13.82 (7.72, 19.92) 18.32 (12.58, 24.06) < 0.001
Model 3 Ref 13.60 (7.51, 19.69) 18.12 (12.37, 23.86) < 0.001
Normal morphology (%)
Crude Ref 1.21 (0.26, 2.16) 2.22 (1.31, 3.12) < 0.001
Model 1 Ref 0.93 (-0.005, 1.87) 2.02 (1.13, 2.91) < 0.001
Model 2 Ref 1.02 (0.09, 1.95) 2.00 (1.12, 2.88) < 0.001
Model 3 Ref 1.05 (0.12, 1.98) 1.95 (1.07, 2.83) < 0.001
  1. Data are presented as β (95 % confidence interval)
  2. P < 0.05 was considered statistically significant
  3. Crude: Unadjusted
  4. Model 1: Adjusted for age
  5. Model 2: Model 1 + educational status, smoking, alcohol consumption, job, and varicocele
  6. Model 3: Model 2 + body mass index and total energy intake