Former President Bill Clinton attempted to defend President Obama’s position on stem cells on prime-time TV and ended up with egg on his face. He was interviewed by Dr Sanjay Gupta, who was filling in for Larry King. Dr Gupta, a practicing neurosurgeon who has also become a media star, reportedly declined the position of Obama’s Surgeon-General, an important advisory post.

But the transcript of the interview suggests that that both men were a bit fuzzy about what an embryo is. Dr Gupta asked Clinton, "as someone who studied this", about the future of human embryonic stem cell research. Mr Clinton’s response suggested that he hadn’t burned the midnight oil over his embryology texts: "I believe the American people believe it's a pro-life decision to use an [IVF] embryo that's frozen and never going to be fertilized for embryonic stem cell research".

Of course, by definition, an embryo has already been fertilised, so this clamoured for clarification. But Clinton repeated the error several times in the course of the interview and was never corrected by Dr Gupta. A softball interview? A slip of the tongue? A senior moment? A tactical ploy to desensitise the public, some bloggers grumbled. But bioethicist Jennifer Miller said that the former President, like the general public, was probably just "confused". Perhaps Presidential confusion about the beginning of human life goes with the territory. Barack Obama famously admitted during the election campaign that determining when a baby gets human rights was "above my pay grade".