Familiarity breeds content? Soothing effect of a familiar odor on full-term newborns

This study tested the effects of familiar and unfamiliar odors during a heel stick in full-term newborns.

Forty-four newborns were exposed to vanillin (via their mother or via their crib) or no odor prior to a heel stick. On the day of the heel stick, infants were either exposed to a familiar odor, an unfamiliar odor, or no odor before, during, and after the procedure. Crying, grimacing, and oral movements were scored.

Infants exposed to a familiar odor displayed little distress and more oral movements during the procedure compared to the unfamiliar group. No advantage was found when infants were exposed to an odor learned via their mother compared to when the odor was learned via the crib. Exposure to an unfamiliar odor did not lessen distress compared to exposure to no odor.

A familiar odor is effective in significantly reducing crying and grimacing during a minor painful procedure. Olfactory support is a useful intervention that may potentially help minimize deleterious effects of neonatal pain.