Australian scientists have found a unique way to determine which embryos stand the best chance of producing a successful IVF pregnancy.
The technique also points to a simple way of determining the gender of a fertilised human egg when it is just days, and only several dozen cell divisions, old.
It relies on taking exact measurements of the nutrients left over in the solution in which embryos are grown before being transferred to a woman's uterus.
"IVF units use this solution, or media as it is known, to provide a bed of nutrients for embryos fertilised in the laboratory from the eggs and sperm of couples who cannot naturally conceive," said Professor David Gardner, head of the Department of Zoology at the University of Melbourne.
"The glucose in embryo solution closely matches that which occurs naturally in the uterus."
Professor Gardner said fertility specialists knew the precise amount of glucose in the solution before an embryo was inserted.
By checking the level of glucose left over on day four or five, and just before implantation, they could see exactly how much of the nutrient load had been consumed by the growing embryo.
"There is clear-cut evidence that the greater the glucose intake, the healthier the embryo," Professor Gardner said.
"By measuring the glucose consumption of an embryo, we can better determine which is the healthiest embryo for transfer back to the patient."
Professor Gardner and his fellow researchers tracked 50 women who were undergoing IVF treatment, starting with an analysis of the media that contained their embryos.
Not all of the women fell pregnant, but of the 28 babies that were born, they were found to be the same "embryos which had the highest glucose uptake" to begin with.
Professor Gardner said another potentially exciting aspect of the research was that female embryos appeared to take up more glucose than male embryos.
"This is a very early observation, but it may have the potential to help identify gender at early embryo stage," he said.
The research will be presented at The Fertility Society of Australia's annual scientific meeting, to be held at the Adelaide Convention Centre.