Table 4.
Sensitive analyses for relative differences in percentage in semen characteristics by delivery mode, the FEPOS cohort, Denmark, 1998–2019
| Semen parameters | Analysis strategies | Number of observations | Delivery mode | Relative differences in percentage | |
|---|---|---|---|---|---|
| Unadjusted model | Adjusted model a | ||||
| % | % (95% CI) | ||||
| Semen volumeb | Model 1f | 806 | Overall CS | 5.6 (− 6.8 to 18.5) | 5.4 (− 5.4 to 17.5) |
| Model 2 g | 691 | Overall CS | 5.5 (− 7.0 to 19.7) | 5.2 (− 6.4 to 18.3) | |
| Model 3 h | 818 | Elective CS (n = 35) | − 4.7 (− 21.8 to 16.0) | − 2.4 (− 16.5 to 14.1) | |
| Emergency CS (n = 52) | 10.9 (− 4.8 to 29.2) | 10.1 (− 6.7 to 30.0) | |||
| Unspecified CS (n = 17) | 11.1 (− 14.5 to 44.5) | 7.8 (− 9.9 to 29.0) | |||
| Total sperm countb | Model 1f | 806 | Overall CS | 0.9 (− 17.4 to 22.3) | − 0.5 (− 14.8 to 16.1) |
| Model 2 g | 691 | Overall CS | − 0.4 (− 19.7 to 23.5) | 0.0 (− 15.9 to 19.0) | |
| Model 3 h | 818 | Elective CS (n = 35) | − 20.0 (− 41.7 to 9.7) | − 16.4 (− 36.7 to 10.5) | |
| Emergency CS (n = 52) | 6.0 (− 18.5 to 37.8) | 7.2 (− 12.0 to 31.0) | |||
| Unspecified CS (n = 17) | 29.4 (− 17.7 to 103.3) | 9.5 (− 22.2 to 54.0) | |||
| Sperm concentrationc | Model 1f | 975 | Overall CS | 5.4 (− 11.7 to 24.2) | 4.6 (− 11.2 to 23.3) |
| Model 2 g | 828 | Overall CS | 3.9 (− 13.4 to 24.4) | 2.5 (− 14.0 to 22.3) | |
| Model 3 h | 988 | Elective CS (n = 41) | − 7.9 (− 29.1 to 21.0) | − 4.5 (− 27.6 to 26.0) | |
| Emergency CS (n = 60) | 13.1 (− 9.6 to 41.3) | 10.8 (− 11.3 to 38.5) | |||
| Unspecified CS (n = 20) | 8.7 (− 26.4 to 60.4) | 4.1 (− 23.1 to 41.0) | |||
| Non− progressive motilityde | Model 1f | 952 | Overall CS | − 6.0 (− 13.8 to 1.3) | − 7.3 (− 13.0 to 0.0) |
| Model 2 g | 812 | Overall CS | − 5.4 (− 12.1 to 2.6) | − 6.8 (− 14.3 to 1.2) | |
| Model 3 h | 965 | Elective CS (n = 38) | − 9.0 (− 19.8 to 3.2) | − 10.8 (− 21.3 to 1.1) | |
| Emergency CS (n = 58) | − 6.7 (− 15.8 to 3.3) | − 7.4 (− 16.0 to 1.2) | |||
| Unspecified CS (n = 20) | 1.9 (− 14.6 to 21.3) | − 1.1 (− 16.8 to 17.9) | |||
| Morphologically normal spermce | Model 1f | 953 | Overall CS | 2.0 (− 11.5 to 17.4) | − 2.1 (− 14.4 to 12.0) |
| Model 2 g | 812 | Overall CS | 1.6 (− 12.8 to 18.3) | − 2.0 (− 15.3 to 13.4) | |
| Model 3 h | 966 | Elective CS (n = 39) | − 19.4 (− 36.7 to 2.7) | − 20.4 (− 39.8 to 5.3) | |
| Emergency CS (n = 58) | 11.4 (− 7.8 to 34.6) | 5.6 (− 9.1 to 22.7) | |||
| Unspecified CS (n = 20) | 15.4 (− 16.5 to 59.4) | 14.3 (− 11.9 to 48.4) | |||
CS caesarean section
aBasic set of variables that were adjusted for all semen parameters included maternal age at delivery, highest socioeconomic status of parents, maternal pre-pregnancy BMI, maternal smoking in the 1st trimester, place of semen sample collection and abstinence time
bFor the analyses of semen volume and total sperm count, 180 samples were excluded due to spillage
cFor the analysis of sperm concentration and morphologically normal sperm, spillage was further adjusted for
dNon-progressive motility was modeled as (non-progressive + immotile spermatozoa) %, and a negative estimate indicated a relatively lower non-progressive motility (ie. higher progressive motility). In the analysis, spillage and internal from ejaculation to analysis were further adjusted for
eFor non-progressive motility and morphology, 17 samples were not available for analyses due to azoospermia
fModel 1: Birth weight z-scores were further adjusted for
gModel 2: Restricted to women without labor induction and pregnancy complications
hModel 3: CS was further classified into elective CS, emergency CS and unspecified CS, and percentage differences were obtained by comparing with the sons born of vaginal delivery