Human newborns prefer human milk: conspecific milk odor is attractive without postnatal exposure.

Behavioral responses of 3- to 4-day-old newborns to the odors of various human milk (HM) and formula milk (FM) were examined in paired-choice tests. When both stimuli were nonfamiliar, breast-fed, as well as bottle-fed, infants oriented their head and mouthed more vigorously to HM than to FM. When breast-fed infants were exposed to nonfamiliar HM along with the familiar FM, their head-turning responses were undifferentiated although they mouthed more frequently to the human stimulus. When nonfamiliar HM and familiar FM were equalized in intensity, nonfamiliar HM again elicited more head orientation and mouthing responses. These results demonstrate that the odor of HM is more attractive to human newborns than FM and that this preference is independent of postnatal feeding experience.