Cortisol and maternal attraction to infant odor

Parturitional hormones activate maternal behavior in most animals but there is little evidence that similar hormones also directly activate positive maternal responsiveness in humans. There is however some indication that cortisol may be involved in the expression of maternal behavior postpartum. Sixty-one postpartum mothers were assessed for their hedonic responses to a variety of odorants including the body odor of their own and other newborn infants. Mothers also provided saliva samples for cortisol (assayed by RIA) before and after a brief interactionʹ with their infants. They also filled out extensive questionnaires assessing their mood, attitudes towards mothering, previous experience caring for infants and indices of maternal attachment. Salivary cortisol levels and change from before to after the interaction were strongly related to indices of maternal attachment. There was a very significant positive relation between cortisol levels and mothersʹ pleasantness ratings of their own infantʹs T-shirt odor. Moreover the extent of decrease in cortisol levels from before to after the interaction was greater in mothers who experienced their infant odors to be more attractive. Our results suggest that cortisol may not only heighten mothersʹ attraction to infant odors but that it also may contribute to mothersʹ emotional and behavioral responses to their new infants in both direct and indirect ways.