We are all aware of the risks of high cholesterol, lack of exercise and stress. But surely there is one part of our lives that should be uncomplicated: the orgasm. Well, apparently not.

Recent evidence suggests that, for both men and women, how we get there has big implications for what it does for us.

For a man, the more wild and thrilling the sex, the closer it is to when he met his mate, the greater his chance of impregnating her. According to a recent Channel 4 documentary, men who are fully stimulated because they are enjoying “gourmet sex” will ejaculate up to 50 per cent more, and with sperm of a better quality. But the way that women orgasm also has important medical implications.

According to Stuart Brody, Professor of Psychology at the University of West Scotland, it is better to orgasm through coital intercourse than by any other route. His premise is that, in terms of evolutionary benefit, this type of orgasm should be favoured since it results in pregnancy.

Over the past five years he has published studies that provide startling evidence to support his idea. In papers, Brody has shown that women who orgasm coitally have lower blood pressure, more sensitive fingers, are slimmer and release four times more of the restorative hormone prolactin after climaxing. He even claims that observers can predict which women commonly orgasm from coital sex just by observing the vivacity of their walks.

When women are wired up to a machine that measures their physical arousal, those who usually orgasm from coitus seem more aware of their bodily state. If they become aroused physically when shown sexy films, they will be more likely to report this than women who usually climax clitorally - indicating that they are more self-aware.

Most controversial of all, Brody has shown that the coitally orgasmic have better mental health and better relationships. He claims they have greater satisfaction from their sex life and more frequent feelings of desire. Indeed, Brody says that that women who never climax coitally are at greater risk of neurosis, schizophrenia and anorexia.

Of course, Brody's work is controversial and raises its own questions. For a start, depending on how you read the evidence, the number of women who orgasm coitally is anywhere between one and two thirds - but the former statistic casts doubt on the evolutionary benefit of female orgasm.

Nonetheless, given a choice, about three quarters of heterosexual women prefer orgasms from coitus rather than clitoral stimulation.

So, assuming that you buy into all this, what does science say is the best way to bring that about? To avoid making men feel like failures, there has been a tendency to play down coital orgasm, but the evidence shows that longer time spent in penetration, rather than foreplay, reaps the best reward.

Half of women will climax if they receive penetration for ten minutes; that rises to two thirds if the man keeps going for more than 15 minutes. An international study suggested that, although we Brits are not in the same league as the Czechs (who keep going on average for 16 minutes), we are not bad. The average was 7.6 minutes for UK men, followed by the Americans, Spanish, Dutch and Turkish - the average Turk took a paltry 3.7 minutes. The conclusion for female readers seeking coital orgasm? A Czech mate.

However, a new study strikes a depressingly pecuniary note. In a large sample of Chinese women, there was a straightforward relationship between how rich a man was and how frequently his partner came.

While the study does not mention the methods used to bring about orgasm, it could be that money might be the most powerful aphrodisiac after all.

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