To think, my Aunt remembers smoking with her OB doctor during a prenatal appointment!
How times have changed, and not so very long ago either.
By the way, everyone justifies behavior they do. EVERYONE. Not just smokers.
I smoked up until the night I found I was pregnant. It wasn't hard for me at that time, I think because I was in such shock. I just stopped. mostly I think because my mother smoked all her life, and I subconsciously didn't want my child viewing me that way. I had tried to quit several times before then but had only made it a couple of days before giving in. : ( I remember the shame I felt that the stupid paper stick had that much control over me.
Denial and addiction can be very very powerful. In my experience smoking is coupled with a black and white outlook. A cycle of recovery and remissions like any other drug.
People bitching at me didn't change me, I had to. I just did it in secret or didn't mention it to them, constantly washing my hands and mouth out, spraying myself with parfume.
OP, you can say things to your friend all you want, but she won't quit unless she wants to. If she's being honest with her medical team, they'll give her more of an earful that she's obviously ignoring anyway.
Also, it can be very very easy to ignore the effects of smoking.
You don't see it, meh, it's not affecting me now. I can quit before it does any damage.
These are the things that go through smoker's heads. Smoker's tell themselves what they want to hear.
Back off and don't shame her, she'll only avoid you and lie. Does this make her a horrible disgusting person? I don't think so. Only very sad. : (