(I sometimes tell this (true) story when talking to medical students or public groups about the ethics of reproductive technology. MPS)
"A couple presented to my office requesting care for infertility and recurrent miscarriages. Within a few visits, it was clear to me and the office staff what the problem was - they were both drug addicts. Their particular addiction was known to increase the risks of infertility and miscarriage, and was associated with a variety of other pregnancy complications. They were in their early 30's and successful in their professions and daily lives. We offered help and strongly recommended that they stop their drug use, but they just wouldn't (or couldn't) do it. How should one proceed in a case such as this?"
Audiences are uniformly unsympathetic towards this couple - no one wants to offer them fertility treatment. Often someone will comment that the situation is appropriate, as drug addicts shouldn't be reproducing anyway. I ask if it matters which drug they are taking, and the answer is "no". Then I reveal that the drug being abused is nicotine - the patients are heavy smokers. At this point some members of the audience become very quiet, as they have packs of cigarettes in their pockets. The rest of the audience usually become less vigorous in their condemnations. No one tries to dispute the harmful effects of smoking on reproduction, but it seems that this addiction is much more socially acceptable than the cocaine or heroine use the audience had in mind.
What ultimately happened with the patients? I finally told them not to come back until they stopped smoking. They never returned.