This study used a saliva test for measuring testosterone. From what I read it doesn't appear that they accounted for diet, weight, and sleep all of which have a

This study used a saliva test for measuring testosterone. From what I read it doesn't appear that they accounted for diet, weight, and sleep all of which have a direct effect on t-levels and will change drastically if a father is active in the care of his newborn. Without good sleep and diet your testosterone could plummet to less than half of your average levels.