From what I've heard, smoking can reduce the likelihood of getting pregnant if one spouse or both spouses smoke. "It can also hurt the antioxidant levels in semen. Antioxidants protect sperm from damage from free radicals, which can affect their motility and ability to fertilize an egg. If a couple is undergoing fertility treatment, poor results during in-vitro fertilization have also been reported when the male partner smokes."
Hope this helps!