Low testosterone in new fathers: Comment from Place

Abstract

In a recent review in TREE, Wynne-Edwards and Reburn 1 suggest that the decrease in serum testosterone levels of new fathers immediately after the birth of a child is associated with the expression of paternal behavior. Another explanation warrants consideration. A key variable that often changes dramatically with the shift from expectant to actual fatherhood is the duration and quality of sleep. Levels of testosterone were lower in men sampled in the three weeks after birth than in men sampled before birth, and sleep deprivation can certainly develop during that interval (personal experience). Sleep deprivation has been associated with a reduction in the concentration of testosterone in men 2, and this might explain the drop in testosterone levels of new fathers. Additionally, the largest decreases in testosterone were noted in men who reported pregnancy symptoms and strong emotional responses to stimuli, such as holding a soft doll wrapped in a soiled receiving blanket, listening to recorded cries and watching a breastfeeding video 3. These findings were taken to suggest that father–offspring interactions cause the decreased testosterone levels observed in new fathers. However, men who are more emotionally involved with the care of their baby are likely to share more in the night-time duties of parenting. Such activity will add to the severity of sleep deprivation, and perhaps to lowering of testosterone levels in these dedicated fathers. The degree of sleep deprivation among new fathers could be controlled for statistically if this confounding variable was measured. Alternatively, one might provide new fathers with supplemental childcare at night (e.g. a nanny) to determine if improved sleep prevents a decrease in testosterone levels in fathers after birth. The pool of expectant fathers who would volunteer for such a study should be vast.