The Effects of Infant Cries and Odors on Sympathy, Cortisol, and Autonomic Responses in New Mothers and Nonpostpartum Women

Abstract

Objective. To determine the biological correlates of maternal responsiveness in new mothers, comparisons were made between new mothers and nonpostpartum women on their affective, hormonal, and heart rate responses to infant cries and odors. Design. Eighty-six new mothers were divided into 3 groups: a cry group who listened to prerecorded cries of newborn infants (n = 27), an odor group who smelled the T-shirts previously worn by newborn infants (n = 28), and the nonstimulation control group (n = 31). Nonpostpartum women also listened to infant cries (n = 30) or no stimuli (n = 30). Salivary samples were taken at 3 time points: prior to and at 20 and 40 min after stimulus session onset. Heart rates were recorded throughout the stimulus session. Results. New mothers were more sympathetic and more alert in response to cries than nonpostpartum women. There were no differences in mothers' responses to odors and control stimuli. Multiparous mothers showed a greater difference in their sympathy to pain versus hunger cries than did primiparous mothers. Mothers who experienced greater sympathy in response to cries had higher baseline salivary cortisol levels and a higher heart rate; in comparison to mothers showing low sympathy, they also underwent a greater decline in cortisol concentrations over the stimulus period. Nonpostpartum women did not show these same affect - physiology relations. These relations were not affected by mothers' social, educational, or economic status, events at the childbirth, or sex of the infant. Conclusions. During the postpartum period, elevations in glucocorticoids and in heart rate facilitate mothers' nurturant and attentive responses to infants and their cues.