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Time-lapse imaging which takes thousands of pictures of developing embryos can boost the success rate of IVF, according to British research.

The method, reported in Reproductive BioMedicine Online, can be used to select embryos at low risk of defects.

Scientists at the CARE fertility group say such informed selection can improve birth rates by 56%.

Other experts say the result is exciting, but the study of 69 couples is too small to be definitive.

The research followed the couples at the CARE fertility clinic in Manchester last year, when 88 embryos were imaged and implanted.

The embryos were put into an incubator and imaged every 10-20 minutes.

The researchers classified the embryos as low, medium or high risk of chromosome abnormalities based on their development at certain key points.

Eleven babies were born from the low risk group (61% success rate) compared to five from the medium risk group (19% success rate) and none from those deemed high risk.

"In the 35 years I have been in this field this is probably the most exciting and significant development that can be of value to all patients seeking IVF," said Prof Simon Fishel, managing director of CARE Fertility Group.

"This technology can tell us which embryo is the most viable and has the highest potential to deliver a live birth - it will have huge potential. This is almost like having the embryo in the womb with a camera on them."

In standard IVF, embryos are removed from the incubator once a day to be checked under the microscope. This means they briefly leave their temperature-controlled environment and single daily snapshots of their development are possible.

Using the time-lapse method embryos don't leave the incubator until they are implanted allowing 5,000 images to be taken.

"Removing embryos from the incubator potentially exposes them to damage, so it must be a good thing to be able to look at the pattern of development over time.

"These results are very interesting but this is is a very small study and any interpretation of the findings must be made with caution as we are dealing with the hopes and expectations of patients," said Dr Virginia Bolton from the assisted conception unit at Guy's and St Thomas' NHS Foundation Trust.

Sheena Lewis, professor of reproductive medicine at Queen's University, Belfast, said: "This may well be the technique we have been waiting for to improve embryo selection and thus success in fertility treatment.

"However, this is a small study with just 46 embryos being followed through to birth. Much more research will be needed before this becomes a routine clinical tool."

Around a dozen private and NHS clinics are using time-lapse embryo imaging. It costs around £750 in addition to about £3,000 for IVF.