<human>: Can you summarize the given text in a few sentences?

So I haven't known Jen (not her real name) for very long, nor has my brother, but they are having a child together and just found out she was pregnant a few weeks ago.  She has several children from previous relationships.  She has pre-emptively expressed contrition for smoking to me (she asked to stop for cigarettes when we were driving somewhere), so I feel like she is prepared to receive and rebute any quit smoking campaigns.  She plans to cut back from her 1-2 packs a day but it doesn't seem like she intends to fully stop.  She is concerned that quitting cold turkey is bad for the baby as well..which I don't buy.  She has told me that she smoked for most, if not all of her other pregnancies and she said they turned out fine. I suppose this is her justification.  

This is a precarious situation for me because we do not know each other very well, and I cannot see a situation where I express my adamant concern for the child's well being without insulting her or her character.  Perhaps that's just the way it has to be.  Ruining a budding relationship between me and my brother's girlfriend could potentially affect my relationship with him. I fear that he may trust her judgement and not have a problem with her smoking.  

I feel like I owe it to this child to speak up and do something, but what is that something?  To what degree of vigilance do I approach this situation?  Is it even any of my business at all? Should I just not say anything?  Any advice or past experience would be appreciated...or links because all I can find is "reasons not to smoke while pregnant, as opposed to "how to tell a pregnant girl to stop smoking"

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<bot>: Bro's new girlfriend is pregnant.  Bro's new girlfriend smokes a pack a day.   What should I do?  Is it even my business?