Couples had sex in MRI scanners in the name of science

In terms of places to have sex and get down and dirty, an MRI scanner doesn't usually top the list.

I mean, great if that's what gets you going but it's not usually the most romantic of hotspots.

However, in the name of science, groups of volunteers did the deed in an MRI scanner in order to give us a proper scientific look at what happens inside the bodies during sex.

There's plenty of places to get intimate, and even in an MRI scanner apparently. (Pixabay)

Eight couples were asked to have sex on the bed inside an MRI scanner while researchers stood in a room next door. According to the study: "The participants were asked to lie with pelvises near the marked centre of the tube and not to move during imaging."

The study, which took place in 1999, produced black and white images that are still popular today according to one doctor. Created for The British Medical Journal (BMJ) in 1999, Dr Tony Delamothe has now discussed the study more than 20 years on.

He explained: "It was hardly the medical equivalent of a moon landing, so why did 'lay' visitors come flocking in such numbers?"

He then suggested that the prospect of seeing sex on screen for free was behind its success, as many realised that even though the images were in black and white and very anatomical, they were still technically pictures of sex.

The black and white images also come with a handy key for identifying what body part is where. (The BMJ)

He added: "If that's the explanation, it's hard to think ourselves back to such an innocent age, given today's explicit online offerings. But it is still making people smile (and laugh), much to the annoyance of author and participant Professor Ida Sabelis. She despairs that friends, family, and even colleagues at VU University in Amsterdam - one of the world's most progressive cities - still find the study amusing.

"Why that's the case, 20 years after the article's original publication, is worth a study of its own."

The images, if you want to see them, show two spines as well as genitalia and show exactly how the male and female bodies fit together during sex. If you wanted to study it more closely, there's even a handy key: P=penis, Ur=urethra, Pe=perineum, U=uterus, S=symphysis, B=bladder, I=intestine, L5=lumbar 5, Sc=scrotum.

The images were taken as part of a scientific study over 20 years ago in 1999.(The BMJ)

The photographs, taken during the missionary position, were also useful scientific studies as they showed that the penis isn't straight during in sex but actually curved to fit the natural curve of the vagina.

Also, scientists had previously thought that the uterus expanded during sex but this was proven that despite female arousal, it doesn't appear to get any bigger.

Whilst the images remain popular more than two decades later, at the time of the study nobody at The BMJ thought the study was particularly useful clinically or scientifically.

However it's now gone on to become one of its most downloaded journal articles of all time, and has been quoted in 130 other scientific papers.