There are many risks with
second hand smoke exposure even for ppl who are not pregnant.
Second hand smoke can cause under developed lungs, increase the chance of sids, low birth weight, baby can develop asthma and a bunch of other things too. Its good your fiance doesn't smoke in the house or around you but he should get into the habbit of not smoking in the car either. The nicotine can settle into the fabrics which is the same as smoking a cigarette while being in the room with the baby.