I was born in 1961. My Dad was a smoker, my Mum wasn't. I can't remember if Dad smoked in the house when we were little. Later, definitely not. What I do remember very clearly is that it was frequently reported on the news from the late 1960s on that doctors and scientists had established a link between lung cancer and smoking and were now advising that smokers should do their level best to give up. I was terrified by this because of my Dad and I desperately wanted him to give up. He managed to cut down a bit, but didn't finally give up until he was in his 50s, by which time he'd probably been smoking for 40 years. Later he got COPD and that affected his health quite badly in the last years of his life, although he did make it to 89.
Now, if it was known that smoking was a risk for lung cancer, it didn't take that much imagination to see that it was probably also a risk for other health problems as well. It was not a huge surprise when research started to show that it was a factor in lots of cancers and also in heart disease. The thalidomide scandal had woken a lot of people up to the fact that anything that got into a mother's bloodstream during pregnancy was likely to end up in the baby's bloodstream too.
I don't know when doctors and midwives started advising pregnant women not to smoke, but it was definitely frowned on in the early 1990s when I was pregnant. I had to buy some cigarettes for my MIL, who was hopelessly addicted but also had dementia, and I felt very uncomfortable about it indeed given that I was heavily pregnant at the time. So I must have expected others to be judging me unfavourably.
I also remember a woman in a neighbouring bed who'd had a very small baby well before the due date, who was in the special care baby unit. She was a smoker who'd had another baby, also premature, less than a year earlier. I knew this because it was all spelled out during the consultant's ward round (no confidentiality at all). The consultant expressed herself very plainly about the smoking (and the back to back pregnancies). I doubt it had much effect.
ETA: no teacher of mine ever smoked in class, either in primary or secondary school. The staffroom was a different matter!