I'm not sure what OP's intentions were in starting this thread, as ragged says the stats are not hard to find. I'm also bored of the debate but I think what is badly missing on MN is genuine support for women who are struggling to quit in pregnancy so I'm going to take this thread in that spirit 
I smoked during both my pregnancies.
First - cut down from 20+ a day to 5 a day. Never quite managed to stop. Smoked in secret, felt shit.
Second - cut down from 15 a day to 5 a day (smoked in secret, felt shit, bla bla) then finally managed to quit altogether at around 6.5 months. Missed it every single bloody day and started again at the first opportunity after the birth.
BF both DC for about 2 years each as a smoker.
They are adults now and appear unaffected by my smoking in pregnancy (yay anecdata!) Meanwhile I have smoked half my teeth out and contributed to an early menopause and possibly also osteoarthritis in my mid-40's. The one biggest effect of my smoking on my DC is that DS took up smoking in adolescence. Children of smokers have 3x higher takeup of smoking than those without a smoking parent.
DS and I have both now switched to vaping. I am hopeful that DS will not relapse and will have done minimal damage to his health from only a few years of smoking. I am also hopeful that I have escaped COPD, lung cancer and heart disease but who knows - problems can show up years after you quit.
If you are pregnant and struggling to quit don't feel ashamed - push for as much help as you need. You should be referred to a specialist midwife or advisor. Don't be fobbed off by a 'brief intervention' (when your MW goes 'smoking is bad m'kay ... risks bla bla bla' but offers no actual help whatsoever). Full NICE guidelines here. Also come on over to MN Stop Smoking section, you'll get lots of support and encouragement and no judgment because we know it doesn't help. Do it for you because you still matter, even when you are pregnant and the risks to you are far greater than any risk to your unborn child.