Table 2.

Comparison of semen parameters among different SDF groups

	Variables	SDF = 1 + 2 (n = 4410)	P	SDF = 1 + 3 (n = 4053)	P
		OR (95%CI)		OR (95%CI)
M1	Abnormal tails	1.09 (1.08—1.10)	< 0.001	1.14 (1.12—1.15)	< 0.001
	Q1	1.00 (Reference)		1.00 (Reference)
	Q2	1.78 (1.41—2.26)	< 0.001	2.35 (1.63—3.39)	< 0.001
	Q3	3.57 (2.86—4.46)	< 0.001	5.23 (3.72—7.36)	< 0.001
	Q4	7.21 (5.76—9.03)	< 0.001	20.93 (15.11—29.00)	< 0.001
	P-Trend	< 0.001		< 0.001
M2	Abnormal tails	1.06 (1.05—1.07)	< 0.001	1.07 (1.05—1.08)	< 0.001
	Q1	1.00 (Reference)		1.00 (Reference)
	Q2	1.49 (1.17—1.90)	0.001	1.55 (1.04—2.31)	0.03
	Q3	2.51 (1.99—3.16)	< 0.001	2.42 (1.66—3.54)	< 0.001
	Q4	3.70 (2.90—4.72)	< 0.001	4.91 (3.39—7.12)	< 0.001
	P-Trend	< 0.001		< 0.001
	Progressive motility
	PR < 10%	1.00 (Reference)		1.00 (Reference)
	10% ≤ PR < 20%	0.94(0.55–1.60)	< 0.001	0.31(0.19–0.50)	< 0.001
	20% ≤ PR < 32%	0.66(0.40–1.09)	< 0.001	0.12(0.07–0.18)	< 0.001
	PR ≥ 32%	0.24(0.14–0.39)	< 0.001	0.02(0.01–0.03)	< 0.001
M3	Abnormal tails	1.06	< 0.001	1.08	< 0.001
	Q1	1.00 (Reference)		1.00 (Reference)
	Q2	1.56 (1.22—1.99)	0.001	1.74 (1.15—2.61)	0.008
	Q3	2.72 (2.13—3.46)	< 0.001	3.03 (2.03—4.51)	< 0.001
	Q4	4.05 (3.12—5.25)	< 0.001	6.31 (4.22—9.44)	< 0.001
	P-Trend	< 0.001		< 0.001

SDF = 1 + 2: the groups with SDF < 20% and of 20% ≤ SDF < 30%; SDF = 1 + 3: the groups with SDF < 20% and of SDF ≥ 30%

M1: no variables adjusted; M2: adjusted for PR and age; M3: M2 additionally adjusted for sperm concentration, total sperm number, normal forms, abnormal heads, and abnormal midpieces

Q quartile, PR progressive motility, SDF sperm DNA fragmentation index