1. A woman smoking around children... well, in spite of my knowing that second hand smoke is more harmful than dragging from the cigarette itself I wouldn't say anything. It's legal and it's a parent's choice to smoke. What would matter is if smoking while driving is considered legal, I guess. I would absolutely say something if I saw someone texting or otherwise using their cell phone while driving and they stopped their car next to mine because that's completely illegal and a hazard to everyone on the road. I'm not sure where cigarettes fall, though, and if it's legal to smoke while driving.
2. A pregnant woman drinking or smoking is legal. It's not advised by medical boards to smoke while pregnant because it's not healthy for mom or baby and can cause low birth weight, problems with lung development, a higher risk for asthma and allergies, etc. Alcohol in excess can cause fetal alcohol syndrome and malformations of the fetus as well as brain damage. BUT small amounts in moderation" are not harmful. With each of my pregnancies I drank before knowing I was pregnant.
With my first pregnancy I attended two weddings that I was in and toasted a single glass of champagne at each (my brother and my husband's sister). I had approval from my OB each time. The rest of the time, I chose not to imbibe.
But had someone had the nerve to say something to me I would have ripped off their arm and beaten them with it. I knew I was safe in what I was doing at those weddings and limited myself to the toasts. My child was born with above average intelligence. My other two daughters are extremely bright as well.
I have great difficulty refraining from saying something if I see someone smoking like a chimney or drinking to excess (getting drunk or drinking more than a single drink) while pregnant. But I have no idea what she's discussed with her doctors, or hell... what if she recently gave birth and still just has flabby baby belly? Or what if she's like my old preschool director and looks perpetually pregnant with twins when her youngest child is in 3rd grade?
But the issue, again, is that smoking and drinking while pregnant are not illegal. Maybe it's immoral to some but this falls under "adult decision making that the government and other adults have no business getting involved in unless they're the baby's father."
3. If I saw someone getting into a car to drive while intoxicated whether they had a child with them or not, any other passenger or just themselves, I would absolutely say something. I've taken keys away from people for that very thing. Hell, one of my best friends threw out my shoulder and tore my rotator cuff because she was cocked off her a$$ drunk and I had to wrestle her to the ground to get her keys (there were additional circumstances... she was extremely drunk and she was very upset over something to boot).
4. If I saw someone slap a baby... well, let's just say that I've said something when I saw someone slap her baby's hand so hard it clearly stung and turned red. I said, "Oh my goodness, I hope everything is all right! I remember that age with my girls." ::strike up conversation about the tough age blah blah blah:: "Your daughter is a cutie pie. You know, though, once when I slapped my eldest daughter's hand I had some random lady come up to me in the store and start shouting at me about how if I slapped too hard I would break the little bones in the baby's hand, especially since I wouldn't know how hard it would take to break them." ::pause and let that sink in::
So yeah, if someone slapped their baby in the face I would say something. I might not be so nice about it as with hand slapping.