The reason is that the question turns out to be not quite as simple as it seems. When US college students were given a list of activities, ranging from kissing to sexual intercourse, and asked to say which of them counted as "having sex", more than half answered that oral sex did not.
The study was fast-tracked to publication in the Journal of the American Medical Association by its distinguished editor, George Lundberg, and appeared last month as members of the US senate began considering whether the sexual high jinks of the President, and his subsequent denials, should result in his impeachment.
Impeccable timing, you might have thought. The majority American view of whether oral sex counts as having sex is surely relevant to the events now unfolding on Capitol Hill. That, however, is not how the luminaries of the American Medical Association saw it. To them, Dr Lundberg's decision to time publication as he did was an unacceptable intrusion into the political process. Dr E Ratcliffe Anderson, executive vice-president of the AMA, said that he did not object to the contents of the paper, but to its accelerated publication. "I happen to believe that Dr Lundberg was focused on sensationalism here, not science," he said.
The sacking has provoked an extraordinary reaction which cannot have been anticipated by the AMA. The story dominated the broadcast media for most of the day on which it was announced, and at least 53 metropolitan newspapers carried it on their front pages. Since then, acres of newsprint have been devoted to the sacking, almost all of it critical of the AMA, which has been depicted as hidebound and out of touch. As the New York Post put it: "I haven't heard recently of any editor being fired for being relevant about what's going on in the world."
On this side of the Atlantic, the British Medical Journal had within 10 days received 67 responses on its website to its comment on the sacking, 55 of which (82 per cent) were outraged by Lundberg's dismissal. Half of these were editors themselves. One, Magne Nylenna, editor of the Journal of the Norwegian Medical Association, suggested establishing a George Lundberg Award for editorial integrity.
There are several bizarre aspects of these events. The first is that the AMA is itself deeply embroiled in national politics. In the last decade, as the St Louis Post-Dispatch observed, the AMA's Political Action Committee has given more than $14m (pounds 8.8m) to political candidates, with about two- thirds going to Republicans. It has also criticised every health reform bill as "socialised medicine". The charge of hypocrisy is difficult to resist.
The second is the suggestion that doctors should keep out of politics. Yet, as most doctors acknowledge, political change over the last half- century has brought greater improvements in health than medical advance - tackling poverty, improving housing and employment.
In terms of public health, timing is critical. A warning about sex or smoking may fall on deaf ears on one occasion and capture the limelight on another, often for reasons that are hard to predict in advance. It depends on linking with other events, riding on a tide of opinion, catching the zeitgeist. In this instance, the Clinton link, as well as being interesting in itself, gave a reasonable chance that the message of the study would be widely disseminated.
Nor is the finding unimportant. It carries a message that goes beyond the parlour games of the chattering classes. (Does sharing a bedroom with a member of the opposite sex count as adultery? Does sharing a bed?) For doctors and other health professionals with an interest in adolescent and sexual health, the issue of what young people understand as "having sex" matters a good deal. It demonstrates that closer and more specific questioning may be necessary to elicit details of activities that could, in the context of Aids and other sexually transmissible diseases, be dangerous.
As one correspondent to the BMJ - Simon Chapman, editor of Tobacco Control - discovered when he questioned his teenage children, fellatio may be commoner than we think.Reuse content