GPX1 is a selenium dependent protein but selenium deficiency would be expected to affect GPX also at the transcriptional level [26] There are however a number of protein to protein interactions that could modulate GPX protein expression at the posttranslational level [12] which could explain the pattern of normal or possibly increased gene expression and decreased protein expression in retained placentas that our results tentatively suggest. Here, GPX1 is linked to selenium deficiency.