Table 1

Summary statistics for biomarkers of reproductive function and potential confounders among 602 male partners of pregnant women

Outcomes and covariatesGreenland (n=199)Warsaw, Poland (n=197)Kharkiv, Ukraine (n=206)p Value†
n*GM (5, 95 P)GM (5, 95 P)GM (5, 95 P)
Male reproductive hormones in serumद
 Follicle-stimulating hormone (IU/L)4564.38 (1.70, 9.20)3.46 (1.40, 7.40)3.67 (1.60, 9.40)0.001
 Luteinising hormone (IU/L)4564.05 (1.80, 8.50)3.81 (1.90, 7.10)3.79 (1.90, 7.60)0.34
 Inhibin B (ng/L)**456184.21 (83.00, 314.00)157.94 (71.00, 275.00)194.74 (98.00, 321.00)<0.001
 Sex hormone-binding globulin (nmol/L)45526.90 (15.60, 46.70)21.61 (9.45, 40.90)26.19 (15.50, 43.20)<0.001
 Total testosterone (nmol/L)**45614.81 (7.27, 24.41)13.08 (6.83, 20.76)18.01 (10.26, 26.89)<0.001
 Free testosterone (nmol/L)**4550.31 (0.18, 0.48)0.29 (0.16, 0.42)0.39 (0.22, 0.58)<0.001
 Estradiol (pmol/L)45463.44 (40.50, 98.70)71.50 (45.80, 112.60)80.73 (52.50, 137.50)<0.001
Conventional semen characteristics
 Semen volume (mL)††,‡‡5353.21 (1.20, 7.20)3.37 (1.25, 7.19)3.29 (1.59, 7.57)0.68
 Sperm concentration (106/mL)††60051.12 (10.75, 199.00)55.95 (7.15, 257.50)53.07 (10.15, 185.80)0.65
 Total sperm count (106/ejaculate)††,‡‡533160.15 (31.50, 692.30)186.68 (18.82, 1061.96)179.46 (34.20, 804.80)0.39
 Morphologically normal (%)**5986.97 (2.00, 13.00)6.66 (2.00, 14.00)7.37 (1.00, 15.00)0.20
 Progressive motility (% A+B)**,††,§§56555.29 (22.00, 81.00)60.98 (19.00, 87.00)55.08 (14.50, 87.00)0.007
Sperm chromatin integrity§,††
 SCSA DNA fragmentation index (%)5467.66 (3.32, 20.28)10.07 (4.16, 31.50)10.83 (3.54, 31.56)<0.001
 High DNA stainability (%)54611.37 (4.37, 29.88)8.66 (3.60, 25.14)10.29 (4.35, 26.55)<0.001
 TUNEL DNA fragmentation index (%)4622.95 (0.79, 13.37)11.64 (2.57, 38.28)6.46 (1.90, 30.18)<0.001
Apoptotic markers§,††
 Fas positivity (%)**45425.00 (2.22, 70.60)48.57 (3.13, 96.42)28.24 (0.00, 90.60)<0.001
 Bcl-xL positivity (%)**28626.54 (0.44, 90.65)18.05 (0.81, 69.64)66.01 (9.54, 99.17)<0.001
Epididymal and accessory sex gland function§,††,‡‡
 Neutral α-glucosidase (mU/ejaculate)44816.32 (4.80, 52.00)21.81 (6.55, 71.52)17.51 (4.86, 52.56)0.001
 Prostate-specific antigen (μg/ejaculate)5073187.74 (1078.00, 8330.85)3708.59 (1312.37, 11127.89)2497.94 (784.08, 7707.70)<0.001
 Zinc (μmol/ejaculate)4974.68 (1.06, 12.63)6.31 (1.50, 25.23)4.22 (1.11, 16.56)<0.001
 Fructose (μmol/ejaculate)50647.00 (12.67, 153.85)42.24 (6.10, 161.65)39.36 (10.69, 117.35)0.18
Y chromosome sperm cells (%)**41151.26 (48.52, 55.49)50.30 (48.79, 52.11)50.76 (48.72, 53.61)<0.001
Age (years)**59731.34 (20.83, 43.15)30.34 (25.36, 36.80)27.88 (20.67, 38.75)<0.001
BMI (kg/m2)**59225.99 (20.56, 31.77)25.81 (20.43, 31.93)24.20 (19.71, 29.41)<0.001
Abstinence period (days)5572.86 (0.50, 7.10)4.27 (1.00, 30.00)3.41 (1.50, 7.00)<0.001
Current smoker, n (%)597144 (72.7%)53 (27.2%)136 (66.7%)<0.001
Current smokers: cotinine (ng/mL)589113.73 (0.96, 465.23)23.95 (<LOD, 358.42)33.59 (<LOD, 447.36)<0.001
Time of blood sampling, <12:00, n (%)50417 (16.8%)187 (94.9%)183 (88.8%)<0.001
  • *Number available out of 602.

  • †Test for difference in levels between the three study populations: ANOVA for means and χ2 test for proportions.

  • ‡In adjusted analyses, adjusted for time of blood sampling.

  • §In adjusted analyses, adjusted for age.

  • ¶In adjusted analyses, adjusted for BMI.

  • **Outcome was not ln-transformed; arithmetic mean presented.

  • ††In adjusted analyses, adjusted for ln-abstinence period.

  • ‡‡Samples with spillage were excluded (n=67 for semen volume and sperm count; n=41–52 for the 4 epididymal and accessory sex gland function markers).

  • §§Samples with a delay of >1 h from collection to semen analysis were excluded (n=28).

  • BMI, body mass index; GM, geometric mean; LOD, limit of detection; P, percentile, SCSA, sperm chromatin structure assay; TUNEL, terminal deoxynucleotidyl transferase dUTP nick end-labelling.