Mother-child bonding is associated with the maternal perception of the child's body odor.

Mothers can recognize the odor of their baby and typically adore this odor. In line with this observation, infant body odors activate reward-related brain areas in the mothers. In some mother-child-dyads however, the mutual bond is impaired and mothers have trouble engaging in interaction with their child. We aimed to examine how mothers with bonding difficulties perceive their child's body odor. In total, 75 mothers of babies aged 0-12 months were examined: Twenty-five of those were recruited in a psychosomatic day hospital ward, which is specialized for mother-child bonding disorders. Fifty age-matched healthy women and their babies served as controls. Body odor samples of each baby were collected from bodysuits in a highly standardized procedure. Thereafter, each mother rated the samples of her own and two other infants in a blind and randomized design. In addition, general olfactory function in terms of threshold and identification ability was tested and the mother reported the bonding to her baby in a standardized questionnaire. Healthy mothers showed a clear preference of their own compared to odors of other infant's, while mothers with bonding difficulties did not. Furthermore, the degree of preference was negatively correlated to self-reported bonding difficulties. Mothers with bonding difficulties could not identify their own infant's odor above chance, while control mothers could. Both groups did not differ in general olfactory function. We assume that reduced close body contact and interaction time associated with bonding difficulties may lead to reduced exposure and hinder the recognition of the infantile body odor. Within a vicious cycle, a reduced hedonic experience smelling their own baby may prevent women from deliberately approaching the baby. Thus, the positive and bond-building consequences of bodily and sensory interaction cannot unfold. As the baby's odor is normally perceived as very pleasant and rewarding, the conscious perception of the infantile body odor may be an additive therapeutic approach for mothers with bonding difficulties.