If you smoke it, yes the smoke is harmful but there are a million other things that are harmful to be around such as
second hand smoke, eating lunchmeat, drinking coffee, changing litter boxes, being around mold, breathing in cleaning products and bleach while cleaning etc. With that being said, pot is illegal and therefore most moms or moms to be are going to be against it. If you do it you are taking a risk and not knowing what it could do.