I think I should refuse to sell cigarettes to a pregnant woman who comes in my store everyday to get another pack.
Giving cigarettes to a pregnant woman can hurt the child, but can you really make that decision for her?
I think it's not such a big deal.
It's not illegal for a pregnant woman to smoke, so I don't think you get to decide that she can't have cigarettes. She may file a complaint against your business. Instead just try mentioning the dangers to her, and leave the rest up to her.
What if I tell her that she can't have cigarettes?
I guess you could try, but she's going to get upset for sure. There might be a law about refusing to sell her something just because she's pregnant. Just try advising her on the risks and let it go.