Table 1.
General characteristics of participants.
| Characteristics | Case | Control | P value |
|---|---|---|---|
| Participants (n) | 549 | 581 | |
| Age (years), median (IQR) | 33.00 (30.00–36.00) | 32.00 (29.00–34.00) | < 0.05 |
| BMI (kg/m2), median (IQR) | 26.17 (23.72–28.73) | 25.95 (23.36–28.73) | 0.36 |
| Physical activity (MET/h/week), median (IQR) | 132.83 (100.70–217.17) | 127.57 (98.35–226.67) | 0.69 |
| Television watching (hours/week), median (IQR) | 3.00 (0.00–10.00) | 3.00 (0.00–10.00) | 0.53 |
| Computer using (hours/week), median (IQR) | 21.00 (14.00–30.00) | 21.00 (14.00–30.00) | 0.56 |
| Abstinence time (days), median (IQR) | 4.00 (3.00–5.00) | 4.00 (3.00–5.00) | < 0.05 |
| Educational level ( n , %) | 0.67 | ||
| Junior secondary or below | 121 (22.04) | 141 (24.27) | |
| Senior high school/ technical secondary school | 79 (14.39) | 82 (14.11) | |
| Junior college/university or above | 349(63.57) | 358(61.62) | |
| Annual family income (RMB thousand yuan) ( n , %) | 0.76 | ||
| < 50 | 98 (17.85) | 94 (16.18) | |
| 50– < 100 | 209 (38.07) | 226 (38.90) | |
| ≥100 | 242 (44.08) | 261 (44.92) | |
| Cigarette smoking ( n , %) | 0.11 | ||
| Yes | 264 (48.09) | 307 (52.84) | |
| No | 285 (51.91) | 274 (47.16) | |
| Alcohol drinking ( n , %) | < 0.05 | ||
| Yes | 199 (36.25) | 250 (43.03) | |
| No | 350 (63.75) | 331 (56.97) | |
| Dietary change before anticipation ( n , %) | 0.17 | ||
| Yes | 127 (23.13) | 115 (19.79) | |
| No | 422 (76.87) | 466 (80.21) | |
| Semen parameters, median (IQR) | |||
| Ejaculate volume (ml) | 3.40 (2.5–4.40) | 3.20 (2.50–4.00) | 0.12 |
| Sperm concentration (106/ml) | 49.13 (33.01–73.44) | 62.26 (42.63–87.59) | < 0.05 |
| Total sperm count (106/ml) | 169.20 (108.4–255.42) | 211.18 (131–297.53) | < 0.05 |
| Progress motility (%) | 23.18 (15.93–28.41) | 43.06 (37.85–50.40) | < 0.05 |
| Total motility (%) | 29.06 (20.77–35.38) | 53.65 (46.44–62.23) | < 0.05 |
| Normal sperm morphology (%) | 5.00 (4.00–7.00) | 6.00 (4.00–8.00) | < 0.05 |
| Diet and related nutrients intake, median (IQR) | |||
| Energy (kcal/day) | 1,731.23 (1,401.51–2,149.24) | 1,683.75 (1,400.51–2,048.60) | 0.12 |
| Proteins (% energy) | 16.49 (15.12–17.77) | 16.46 (15.17–17.78) | 0.79 |
| Fat (% energy) | 24.99 (21.68–27.95) | 24.73 (22.06–27.98) | 0.74 |
| Carbohydrates (% energy) | 57.29 (52.76–62.23) | 57.27 (52.09–61.39) | 0.08 |
| Total dietary fiber (g/1,000 kcal) | 8.99 (7.45–10.92) | 8.74 (7.23–10.65) | 0.07 |
| Sodium (mg/1,000 kcal) | 637.83 (547.96–754.00) | 602.39 (505.25–723.28) | < 0.05 |
BMI, body mass index; MET, metabolic equivalent of task; IQR, interquartile range.
All continuous variables were shown as the mean and standard deviation. P values were determined with the Kruskal-Wallis or chi-square test. All statistical tests are two sided.