Abstract
Mothers are attracted to the body odor of newborn infants. In addition, we have previously reported that the body odors of newborn infants exert effects on moods in postpartum 4–5 days mothers, but little is known about its reason. In the present study, we examined whether their hormonal status influenced the effects of the body odors of newborn infants. The body odors were collected from the 3-day-old infants and 1-month-old infants from their undershirts. Four–five days postpartum mothers (exp. 1) and 1-month postpartum mothers (exp. 2) were exposed to odors of a part of the undershirt with a) control odors, b) their own infant body odors or c) other infant body odors. We used the visual analog scales (VAS) to assess the effects of infant body odors on postpartum moods and collected blood samples to measure their hormonal status. This study was approved by the ethics committee of Nagasaki University. The newborn infant body odors significantly decreased anxiety, depression and fatigue scores, whether infant odors may be originated from their own infants or other infants (exp. 1). However, there were no significant effects of the other infant odors on 1-month postpartum mothers (exp.2). These results suggest that the calming effects on postpartum mother are involved in their sensitivity to the olfactory cue, so that we measured their hormonal status to explore the difference between postpartum day 4-5 and 1-month. [J Physiol Sci. 2008;58 Suppl:S136]
