Table III.
Estimated percent changes and 95% CIs for semen quality parameters associated with underweight, overweight and obesity compared with normal weighta.
| Characteristic | Underweight (n = 1815) | Normal (n = 22 762) | Overweight (n = 5070) | Obese (n = 302) | |||
|---|---|---|---|---|---|---|---|
| Percent change (95% CI) | P | Percent change (95% CI) | Percent change (95% CI) | P | Percent change (95% CI) | P | |
| Semen volume, ml | −3.6 (−7.7, 0.7) | 0.10 | 0 (ref.) | −4.2 (−6.8, −1.6) | 0.002 | 6.0 (−4.3, 17.5) | 0.27 |
| Sperm concentration, 106/ml | −3.0 (−5.8, −0.1) | 0.042 | 0 (ref.) | 0.3 (−1.5, 2.2) | 0.72 | 1.7 (−5.1, 9.0) | 0.63 |
| Total sperm number, 106 | −6.7 (−11.3, −1.9) | 0.007 | 0 (ref.) | −3.9 (−6.9, −0.9) | 0.012 | 7.1 (−4.6, 20.9) | 0.24 |
| Total motility, % | −0.7 (−2.1, 0.7) | 0.32 | 0 (ref.) | 0.3 (−0.6, 1.3) | 0.46 | 1.1 (−2.2, 4.6) | 0.51 |
| Progressive motility, % | −0.6 (−2.1, 1.0) | 0.47 | 0 (ref.) | 0.6 (−0.4, 1.6) | 0.25 | 1.1 (−2.6, 4.9) | 0.56 |
| Total motile sperm count, 106 | −7.4 (−12.4, −2.2) | 0.006 | 0 (ref.) | −3.6 (−6.9, −0.2) | 0.036 | 8.9 (−4.3, 24.0) | 0.20 |
N refers to the number of subjects in each BMI category.
aBMI was categorized using the WHO criteria: underweight (<18.5 kg/m2), normal weight (18.5–24.9 kg/m2), overweight (25–29.9 kg/m2) and obese (≥30 kg/m2). The number of underweight, normal weight, overweight and obese subjects were 222, 3046, 660 and 38, respectively.
Linear mixed models were used to estimate percent changes and 95% CIs with adjustment for age, ethnicity, education, smoking, marital status, abstinence period and season.