Table 3.
Crude and adjusteda (95% confidence intervals) relative risks of low semen characteristics according to WHO’s lower reference limits and low testes volume according to categorised maternal vitamin D concentrations and continuously modelled maternal vitamin D (nmol/L) in 827 participants from the Fetal Programming of Semen Quality (FEPOS) Cohort, 1998–2019, Denmark
| nb | nmol/L | Crude | Adjusted (95% CI) | |
|---|---|---|---|---|
| Semen characteristics | ||||
| Volume < 1.5 mLc | 653 | > 75 | Ref | Ref |
| 50–75 | 1.4 | 1.2 (0.6 to 2.2) | ||
| 25–50 | 1.2 | 1.1 (0.6 to 2.0) | ||
| < 25 | 1.9 | 1.6 (0.7 to 3.5) | ||
| Per 10 nmol/L lower vitamin D | 1.1 | 1.1 (1.0 to 1.2) | ||
| Concentration < 15 mill/mL | 787 | > 75 | Ref | Ref |
| 50–75 | 0.7 | 0.7 (0.5 to 1.0) | ||
| 25–50 | 0.9 | 1.0 (0.6 to 1.4) | ||
| < 25 | 0.9 | 0.9 (0.5 to 1.5) | ||
| Per 10 nmol/L lower vitamin D | 1.0 | 1.0 (0.9 to 1.1) | ||
| Total sperm count < 39 millc | 653 | > 75 | Ref | Ref |
| 50–75 | 1.2 | 1.1 (0.7 to 1.7) | ||
| 25–50 | 1.2 | 1.2 (0.8 to 1.9) | ||
| < 25 | 1.9 | 1.5 (0.9 to 2.7) | ||
| Per 10 nmol/L lower vitamin D | 1.1 | 1.1 (1.0 to 1.2) | ||
| Progressive motility < 32%d | 771 | > 75 | Ref | Ref |
| 50–75 | 0.8 | 0.9 (0.4 to 1.9) | ||
| 25–50 | 0.3 | 0.3 (0.1 to 0.9) | ||
| < 25 | 1.3 | 1.2 (0.5 to 3.2) | ||
| Per 10 nmol/L lower vitamin D | 0.9 | 1.0 (0.8 to 1.1) | ||
| Morphology < 4% normal | 770 | > 75 | Ref | Ref |
| 50–75 | 1.2 | 1.4 (1.0 to 2.0) | ||
| 25–50 | 1.0 | 1.2 (0.8 to 1.7) | ||
| < 25 | 1.1 | 1.2 (0.7 to 2.0) | ||
| Per 10 nmol/L lower vitamin D | 1.0 | 1.0 (1.0 to 1.1) | ||
| Testes volume | ||||
| TAverage testes volume < 15 mL | 794 | > 75 | Ref | Ref |
| 50–75 | 1.2 | 1.2 (0.9 to 1.6) | ||
| 25–50 | 1.2 | 1.2 (0.9 to 1.6) | ||
| < 25 | 1.4 | 1.4 (1.0 to 1.9) | ||
| Per 10 nmol/L lower vitamin D | 1.0 | 1.0 (1.0 to 1.1) |
All analyses are adjusted for socioeconomic status (highest of the parents), couple fecundity, maternal age at delivery; maternal pre-pregnancy body mass index; maternal first trimester smoking and season of clinical visit. Semen characteristics are further adjusted for abstinence time; place of semen sample collection and spillage. Testes volume are further adjusted for abstinence time
Numbers correspond to the adjusted models. The number of sons contributing to each analysis vary due to missingness (due to spillage or azoospermia)
Excluding samples with spillage
Further adjusted for interval between ejaculation and analysis (minutes)