Because of the chemical nature of impulse and the axon-dendrite structure. Because of the chemical nature of impulse and the axon-dendrite structure. http://www.biologymad.com/nervoussystem/nerveimpulses.htm (Best technical explanation and excellent graphics and animations)
Newborns may sneeze, and this is typically attributed to the irritation of their nasal passages. The most common irritants, explains Dr. Iannelli, are smoke (and simply smoking outside is not enough), animal dander from pets in the house, dust mites, and mold.
He does not know how to sniff it in or blow his nose and sneezing during the first few months is common, it is the only way that the baby can clear his nose. Remember, he has to get used to a lot of new stuff such as breathing and swallowing and burping etc. So for the most part, newborn sneezing is no cause for worry.