1. The common cold is caused by viruses, or germs, that infect the nose, throat, and sinuses.
2. Cold germs spread easily. Babies are continually touching things that may have germs on them, such as their noses, eyes, and mouths.
3. Babies also put things, such as toys, in their mouths, and touch other babies while they are playing. Cold viruses can live on objects for several hours and can be picked up on the hands of other babies who touch the same object. If your baby touches something with cold bacteria and then touches your mouth, eyes, or nose, the bacteria can infect your baby.
4. Parents and caregivers who regularly welcome their children, change diapers, and nourish their babies can also catch the common cold virus and infect their babies with bacteria.
5. Some cold viruses float in the air when a sick baby coughs or sneezes. Droplets of cold bacteria from a cough or sneeze can reach the nose and mouth of another baby.
Source by - my.clevelandclinic.org