IVF trial tests frozen embryo transfers:

Currently, women undergoing in vitro fertilisation have fresh embryos implanted after using hormones to stimulate the ovaries to produce more eggs.

However, any collected embryos that are not immediately used are frozen and can be implanted at a later date if the first cycle is unsuccessful, or for patients trying for another baby after a successful pregnancy.

IVF clinic Genea claims its success rates for frozen embryos are now on par with fresh embryos.

The trial is investigating the advantages of transferring a frozen embryo into the uterus during a natural menstrual cycle rather than straight after the use of hormone drugs, when the lining of the uterus might not be as receptive.

"The transfer of a fresh rather than a frozen embryo has been the traditional model for IVF and is promoted by some clinics as the `gold standard'," Genea medical director Associate Professor Mark Bowman said in a statement.

"But the best and quickest way to achieve a healthy baby may be from transferring a single frozen and thawed embryo."

The study involving 200 patients comes after an Australian study published last month found that birth defects were significantly decreased among IVF babies conceived from a frozen rather than a fresh embryo.