Fig 2. Forest plots of MTHFR 677C>T polymorphism and male infertility risk (CT+TT vs. CC).

[A for overall populations; B for ethnicity subgroup; C for sperm concentration subgroup; D for control sources subgroup]. The squares and horizontal lines correspond to the study-specific OR and 95% CI. The area of the squares reflects the study-specific weight (inverse of the variance). Diamonds represent the pooled OR and 95% CI. ^athe 37^th reference, ^bthe 49^th reference