All interesting points. That's 150,000 women a year . These women continue to do so in the face of campaign after campaign on the evils of smoking. The answer is that if you smoke very little, there will probably be no detectable effect on your unborn child. With women who smoke heavily, the effects tend to be more obvious.
Babies tend to be smaller.
They are more at risk of deformities. They are more prone to asthma. They might be less clever. They are more likely to die in their cot. And, of course, the mother is more likely to miscarry.