Can second hand smoke harm unborn baby

I'm still in my TWW window, but I have a feeling this could be my month. Anyway my MIL smokes a pack per day and we went to visit yesterday...the whole time I'm thinking what if I'm pregnant and she could be harming our baby! 😳 she's the only one that smokes in the immediate family and she knows people hate the  fumes blowing near them but eh she doesn't seem to care much. If I am preggers I'm sure she wouldn't mnd if I told her not to smoke around me.