British doctors are testing a breakthrough IVF device that could allow fertilisation to take place in the womb rather than the lab.

Would-be parents are being offered a new form of IVF which allows fertilisation to take place inside the womb instead of in a laboratory.

It is hoped the new technique, being used for the first time in the UK, will not only be a psychological boost to parents but also have health benefits by potentially improving the birth weight of IVF babies.

The technique, which uses a device called AneVivo, involves placing egg and sperm cells within a tiny capsule which is placed painlessly into the womb for 24 hours, during which time embryos begin to develop.

Doctors then remove the device, which is around 1cm long and 1mm wide, and, after two to four days, select the embryos that are healthy enough to be implanted back into the lining of the womb in the hope of achieving a pregnancy.

With conventional IVF treatment, eggs are removed from the ovaries and fertilised with sperm in a laboratory before doctors select the embryos to return to the womb to continue the treatment process.

Professor Nick Macklon, medical director at Complete Fertility Centre Southampton, which is located within the city's Princess Anne Hospital, said: "The introduction of this device signals a real breakthrough in IVF treatment as it enables women to care for an embryo in its earliest stages of development for the first time.

"That is important psychologically as it involves parents-to-be directly with the fertilisation process and early embryo development but, perhaps more importantly, it also could provide many potential health benefits for babies born following fertility treatment."

Macklon, who was involved with the development of the device, said research was ongoing into the long-term health of babies born following fertility treatment and whether or not it could be improved by a reduction in the time spent in the laboratory.

He explained: "Babies born following IVF treatment have been shown to have lower than normal birth weight and, although not initially a problem, we know there is a link between low birth weight and long-term health and the laboratory environment could play a part in this.

"Through the use of AneVivo, in addition to the fact fertilisation takes place in the natural environment of the womb with access to nutrients and signals from the mother, we can reduce exposure to the synthetic culture fluids used in the laboratory and help to determine precisely what effect this may have."