By David Spiegelhalter 15 March Sex: But like so many other fun activities, it carries its fair share of risks. Unwanted pregnancies and getting a nasty disease are the obvious ones, but there is also the risk of having a heart attack, getting injured when the bed collapses, even the chance of arrest in flagrante in a public place. So, what appears to be a simple act for some, at least is actually rather more complex. And that means we can begin to look for juicy numbers to find out just how risky things are in the bedroom.
Let us start, as most of us did, with simple, unprotected sex between a man and a woman, and ask: This, for understandable reasons, is rather difficult to study under laboratory conditions — a New Zealand study in which participants were only allowed to have sex once a month suffered, unsurprisingly, with a high dropout rate. Perhaps the closest we have to a robust figure is from a European study that recruited young couples who did not use artificial contraception and who carefully recorded the day of every act and there were a lot of them until there had been pregnancies.
The simplest way to estimate the chance of pregnancy was to consider only cycles in which there had been only one act of intercourse.
The bottom line is that a single act of intercourse between a young couple has on average a one in 20 chance of pregnancy — this assumes the opportunity presented itself on a random day, as these things tend do when you are young.
Calculating success So, given this, what are the chances of success for an average couple trying to have a child? People who study how populations change are called demographers, and they use the rather academic term to describe the chances of becoming pregnant during one menstrual cycle: If we assume each month is the same and independent, then there is a 0. Reducing risk But suppose you do not actually want to get pregnant — how effective are different types of contraception?
This is generally expressed as pregnancy rate following one year of use, and strongly depends, of course, on the care with which precautions are taken. Such figures are particularly important when trying to minimise the incidence of unwanted teenage pregnancies. In in England 41, girls aged conceived.
That is 47 in every 1, girls, or 1 in every 21 — or to put it in more stark terms, one girl in every average-sized school class. Forty-nine percent of these teenage pregnancies end in abortions, but that still leaves many actual teenage births. This is in staggering contrast to countries such as Korea, Japan, Switzerland, the Netherlands and Sweden, which all have birth rates of fewer than seven per 1, teenagers.
The Netherlands is just over the channel from the UK and yet their youth clearly have a very different approach to sex. Unfortunate end Finally, we should never forget the risks of such an energetic pursuit. Last year, researchers estimated that 1 in 45 heart attacks are triggered by sexual activity.
Solo sexual activity used to be associated with blindness and stunted growth, for which there is a limited evidence-base to say the least. But if it involves asphyxiation it is not recommended for the cautious, with numerous fatalities recorded, including the actor David Carradine, singer Michael Hutchence and a UK Member of Parliament. One study recorded as many as deaths from just two provinces in Canada. The moral of all this is, possibly, that sex can be just as much about risk as morality.
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