Smoking and Fertility? do you know someone who had a bad smokin habit and still got pregnant?

Ok, so I have a ttc buddy who smokes at least a pack of ciggs a day. Im wondering if thats the reason why shes not getting preggers. I tried to tell her that this could be the problem and she goes on to say there are junkies in the street who gets pregnant everyday. plus she promises to quit after she gets pregnant. can smoking make a person sterile?