Meconium is generally regarded as potentially toxic waste material, but some of its known components, e.g. bilirubin, may also function as antioxidants. We postulated that human meconium could have a potential role in the perinatal tolerance to oxidative stress and therefore studied the antioxidative capacity of pooled and lyophilized meconium collected from 40 healthy term infants in vitro.

When compared to three potent antioxidants vitamin C, vitamin E-analog, and a synthetic antioxidant, butylated hydroxytoluene, meconium showed a significant superoxide trapping and peroxidation prevention capacity, but its capacity to trap peroxyl radicals was minor. These effects of meconium were possibly due to bilirubin and ubiquinone, both found to be present in high concentrations in meconium. No vitamin A or E was detected in meconium.

These novel findings are consistent with the hypothesis that human meconium has a physiological role as an important endogenous antioxidant during perinatal transition.