Comparison 1.

Antioxidant(s) versus placebo or no treatment/standard treatment

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Live birth; antioxidants vs placebo or no treatment/standard treatment (natural conceptions and undergoing fertility treatments)	8	651	Odds Ratio (M‐H, Fixed, 95% CI)	2.13 [1.45, 3.12]
1.1 Placebo	5	388	Odds Ratio (M‐H, Fixed, 95% CI)	2.01 [1.17, 3.44]
1.2 No treatment	3	263	Odds Ratio (M‐H, Fixed, 95% CI)	2.26 [1.31, 3.91]
2 Live birth; type of antioxidant	8		Odds Ratio (M‐H, Fixed, 95% CI)	Subtotals only
2.1 N‐acetyl‐cysteine	1	60	Odds Ratio (M‐H, Fixed, 95% CI)	3.0 [1.05, 8.60]
2.2 L‐arginine	1	37	Odds Ratio (M‐H, Fixed, 95% CI)	0.43 [0.09, 2.09]
2.3 CoQ10	1	39	Odds Ratio (M‐H, Fixed, 95% CI)	0.82 [0.19, 3.54]
2.4 Vitamin D	1	52	Odds Ratio (M‐H, Fixed, 95% CI)	0.79 [0.21, 3.02]
2.5 Vitamin B complex	1	102	Odds Ratio (M‐H, Fixed, 95% CI)	2.07 [0.93, 4.57]
2.6 Combined antioxidants	2	258	Odds Ratio (M‐H, Fixed, 95% CI)	6.76 [2.79, 16.41]
2.7 Vitamin E	1	103	Odds Ratio (M‐H, Fixed, 95% CI)	1.43 [0.50, 4.10]
3 Live birth; indications for subfertility	6		Odds Ratio (M‐H, Fixed, 95% CI)	Subtotals only
3.1 Polycystic ovary syndrome	3	362	Odds Ratio (M‐H, Fixed, 95% CI)	3.34 [1.90, 5.86]
3.2 Tubal subfertility	1	37	Odds Ratio (M‐H, Fixed, 95% CI)	0.43 [0.09, 2.09]
3.3 Varying indications	1	58	Odds Ratio (M‐H, Fixed, 95% CI)	4.5 [1.46, 13.86]
3.4 Unexplained subfertility	1	103	Odds Ratio (M‐H, Fixed, 95% CI)	1.43 [0.50, 4.10]
4 Live birth; IVF/ICSI	4	230	Odds Ratio (M‐H, Fixed, 95% CI)	1.21 [0.69, 2.11]
5 Clinical pregnancy; antioxidants vs placebo or no treatment/standard treatment (natural conceptions and undergoing fertility treatments)	26	4271	Odds Ratio (M‐H, Fixed, 95% CI)	1.52 [1.31, 1.76]
5.1 Placebo	12	2444	Odds Ratio (M‐H, Fixed, 95% CI)	1.47 [1.20, 1.82]
5.2 No treatment/standard treatment	15	1827	Odds Ratio (M‐H, Fixed, 95% CI)	1.57 [1.27, 1.93]
6 Clinical pregnancy; type of antioxidant	26		Odds Ratio (M‐H, Fixed, 95% CI)	Subtotals only
6.1 N‐acetyl‐cysteine	6	1354	Odds Ratio (M‐H, Fixed, 95% CI)	1.22 [0.92, 1.63]
6.2 Combined antioxidants	4	569	Odds Ratio (M‐H, Fixed, 95% CI)	2.28 [1.51, 3.43]
6.3 Melatonin	4	568	Odds Ratio (M‐H, Fixed, 95% CI)	1.29 [0.91, 1.83]
6.4 Vitamin E	1	103	Odds Ratio (M‐H, Fixed, 95% CI)	1.43 [0.50, 4.10]
6.5 Ascorbic acid	1	619	Odds Ratio (M‐H, Fixed, 95% CI)	0.75 [0.50, 1.14]
6.6 L‐arginine	2	71	Odds Ratio (M‐H, Fixed, 95% CI)	1.05 [0.32, 3.46]
6.7 Myo‐inositol plus folic acid	4	694	Odds Ratio (M‐H, Fixed, 95% CI)	1.35 [0.98, 1.86]
6.8 CoQ10	2	149	Odds Ratio (M‐H, Fixed, 95% CI)	4.28 [1.79, 10.26]
6.9 L‐carnitine	1	170	Odds Ratio (M‐H, Fixed, 95% CI)	82.05 [10.92, 616.59]
6.10 Vitamin D	1	52	Odds Ratio (M‐H, Fixed, 95% CI)	0.83 [0.25, 2.76]
6.11 Vitamin B complex	1	102	Odds Ratio (M‐H, Fixed, 95% CI)	1.94 [0.82, 4.58]
6.12 Myo‐inositol plus melatonin plus folic acid	1	389	Odds Ratio (M‐H, Fixed, 95% CI)	1.38 [0.90, 2.12]
7 Clinical pregnancy; indications for subfertility	22		Odds Ratio (M‐H, Fixed, 95% CI)	Subtotals only
7.1 Polycystic ovary syndrome	11	1721	Odds Ratio (M‐H, Fixed, 95% CI)	2.63 [2.06, 3.36]
7.2 Unexplained	3	967	Odds Ratio (M‐H, Fixed, 95% CI)	0.82 [0.59, 1.14]
7.3 Tubal subfertility	2	71	Odds Ratio (M‐H, Fixed, 95% CI)	1.05 [0.32, 3.46]
7.4 Varying indications	5	1004	Odds Ratio (M‐H, Fixed, 95% CI)	1.27 [0.94, 1.71]
7.5 Poor responders	1	65	Odds Ratio (M‐H, Fixed, 95% CI)	1.88 [0.64, 5.47]
8 Clinical pregnancy; IVF/ICSI	15	2263	Odds Ratio (M‐H, Fixed, 95% CI)	1.19 [0.98, 1.43]
9 Adverse events	20		Odds Ratio (M‐H, Fixed, 95% CI)	Subtotals only
9.1 Miscarriage	18	2834	Odds Ratio (M‐H, Fixed, 95% CI)	0.79 [0.58, 1.08]
9.2 Multiple pregnancy	8	2163	Odds Ratio (M‐H, Fixed, 95% CI)	1.00 [0.73, 1.38]
9.3 Gastrointestinal disturbances	3	343	Odds Ratio (M‐H, Fixed, 95% CI)	1.55 [0.47, 5.10]
9.4 Ectopic pregnancy	1	58	Odds Ratio (M‐H, Fixed, 95% CI)	2.90 [0.11, 74.13]
9.5 Headache	1	170	Odds Ratio (M‐H, Fixed, 95% CI)	2.02 [0.18, 22.75]