According to research, IVF babies born from frozen embryos are healthier than those who develop from fresh embryos. Three studies that were presented at the American Society for Reproductive Medicine conference in San Francisco, said that babies from frozen embryos were less likely to be premature or under weight.

A study from Finland said that babies born from fresh embryos had a 35 % higher chance of being premature and were 64 % more likely to have a lower birth weight than those born from frozen embryos.

The second study from the University of Pennsylvania in Philadelphia, found that babies born from fresh embryos had a 51 % higher chance of having lower birth weight and were 15 % more likely to die at the time of birth as compared to babies born from frozen embryos.

The third study by the Royal Women's Hospital in Melbourne, Australia, found 11% of babies born from fresh embryos had low birth weight as compared with 6.5% of babies born from frozen.

A total of 12.3% of babies born from fresh embryos were premature, as compared with 9.4% of those born from frozen, while 1.9% died as compared with 1.2% from frozen. The results were said to be related to the quality of the placenta, the digestive and respiratory system of the fetus.

Research done previously has suggested that these findings could be due to the fact that only the strongest embryos survive the freezing process.

Dr Allan Pacey, a fertility expert from the University of Sheffield and secretary of the British Fertility Society said, "Frozen embryo transfers are not as successful as fresh ones in terms of getting a pregnancy. So it may be that we have to balance the health of children against chances of success."

He added: "It is intriguing research that goes against what we would normally assume. It now needs to be looked at again."