A systematic review of 14 clinical trials involving 1,087 preterm infants looked at whether exposing these babies to different smells could improve their health outcomes. The odors tested included maternal breast milk, food-related scents like cinnamon and vanilla, and non-food smells such as rose or a parent's scent. The researchers compared these to no smell, a placebo, or standard care.
The results were mixed. For infants exposed to maternal breast milk odor, there was a slight reduction in the time needed to achieve full oral feeding—about 1.7 days less on average. However, there was no clear effect on the number of daily apnea episodes or the total length of hospital stay. When food-associated odors were used, the number of apnea episodes dropped by about 2 per day, but hospital stay and feeding time were not clearly improved.
Non-food odors, like a parent's scent, showed a possible benefit: hospital stays were about 3.2 days shorter on average, and apnea episodes also decreased. However, the quality of the evidence for all these findings was rated as very low to low, meaning the results are uncertain and could change with more research.
The review did not report any side effects or safety issues, but the studies had limitations such as small size and indirect measurements. Because the evidence is weak, these findings should not be used to change clinical practice yet. More rigorous studies are needed to confirm whether smell therapy is truly helpful for preterm infants.