St George's Hospital in South London hopes to make thousands of pounds by selling the videos to parents keen to own a unique record of the first months of their baby's life.

Ultrasound: a unique record

Ultrasound scans are routinely done at three months when the foetus is already well developed, and there is a heart beat. The scan is carried out to ensure that the foetus does not have any abnormalities.

Mother to be Kristy Barnes said: "I did not expect to see hands and feet waving about in the air, and a mouth opening. You only see it once when you come in, if you take it home you can watch it all the time."

However, legal experts have warned the hospital risks the videos being used as evidence in legal action should anything go wrong with a pregnancy and an abnormality has not been detected.

Legal evidence

Solicitor Terry Lee said: "The court are going to have regard to every piece of information. I cannot envisage the court saying we will not bother to see what is on this video film because it is a memento. That is absolutely not going to be the case.

"That video could well prove very important in a court case."

But Professor Eves Ville, director of foetal health at St George's, said: "The medical examination is carried out beforehand and we give the results of the scan before we make the video.

"Those few minutes are just for the family. They are nothing like a medical document."