Acute - Very contagious and needs antibiotics, can be passed on like a cold.
Chronic - Can not be passed on, this is a more severe level of irritation. Caused from years of inflammation of the air way.
For the most part, it will effect you but not the baby, since it forms in your lungs. Talk to your doctor and they may be able to give you a breathing treatment or medicine to make you feel better.
Bronchitis is contagious. I have a friend whos hisband and son both get it really bad and when one shows a sign she puts a mask on herself and her littlest. The husband and older son that are both prone she does not try to prevent because they are both so susceptible to it they get it regardless. I dont know about the harm to baby, however.