Seventeen-year-old Bristol Palin must be the best-known unmarried teenager mother in the world. The media frenzy over her five-month-old pregnancy began when her mother, Republican vice-presidential candidate Sarah Palin, announced that her daughter was going to have a child and to marry the father. She asked the media to respect the family’s privacy. Not much chance of that. Within days journalists had tracked down the 18-year-old father, Levi Johnston, and were camping outside his family’s home. Both Bristol and Levi are to attend GOP convention in Minneapolis.

Has there ever been a pregnancy so politically charged? Sarah Palin was selected by Senator John McCain as his running mate because of her impeccable pro-life, pro-family, Christian principles, in addition to her strength of character and her conservative politics. For the Christian vote, his choice was straight out of central casting.

But according to the mountains of commentary in the media, the teen’s pregnancy may have tarnished Mrs Palin’s halo. How could this happen in a Christian household? Isn’t it inconsistent with family values? Shouldn’t a Christian wife and mother be spending her time at home looking after her kids? As far as BioEdge can gather from surfing newspaper comment and blogs, the reaction supports the notion that Americans are in the middle of a culture war. Republicans and Christians are saying, that’s life in modern America, and have heaped praise upon the girl and her family for not aborting the child. Democrats and some liberal media have gasbagged on the gulf between Christian principles and social realities.

Which is really the point of the story. The only remotely bioethical issue on which everyone has an opinion is teen pregnancy. Not abortion, not stem cell research, not euthanasia, not IVF. Another bioethical story cropped up in the campaign at one stage, but it quickly disappeared – the two IVF children of John and Elisabeth Edwards. But a teenager’s out-of-wedlock pregnancy is seen as a major ethical issue.

As William Saletan pointed out in the online magazine Slate, the odds are that Bristol Palin is not the only pregnant teenager whose dad was running for president since 1964. "If you're a politician, and your daughter gets pregnant out of wedlock, you can be systematically excluded from the sample of nominees by self-selection, voters, or running-mate vetters. But not if the pregnancy never becomes known... Remember that before you judge or poke fun at Sarah Palin. She's not the candidate whose daughter messed up. She's the candidate who didn't get rid of the mess." Pessimistic, perhaps, but possible.