TUESDAY, May 13 (HealthDay News) -- Researchers say DNA tests may be able to tell doctors which embryos tabbed for in vitro fertilization (IVF) are most likely to result in the births of healthy babies.

The technique, discussed in a report published online May 14 in Human Reproduction, could also help fertility experts prevent accidental multiple pregnancies in their IVF patients.

A woman's eggs are fertilized with sperm during IVF and then allowed to develop in the laboratory for about five days until they reach the blastocyst, or very early embryo, stage. Doctors then decide which blastocysts look most likely to develop successfully and how many to put into the woman's womb.

Since reliable tests for determining which blastocysts are viable do not exist, couples often choose to have more than one blastocyst implanted in the woman's womb. While this increases the chances of a successful pregnancy, it also raises the risk of a woman becoming pregnant with two or more babies at once. Multiple pregnancies bring added dangers to the mother and babies.

In the study, researchers removed cells from the blastocysts being developed for 48 women, 25 of whom later became pregnant from the fertilized eggs resulting in 37 babies being born. The DNA from these cells was matched with the babies' DNA, thereby telling researchers which blastocysts developed into babies.

In analyzing the expression of genes in the viable and non-viable blastocysts, the team noted differing patterns. The genes expressed in the viable blastocysts, for example, are involved in cell adhesion, cell communication, cellular metabolic processes and response to stimuli -- all key processes involved in embryo implantation.

This finding could lead to doctors being able to select the single most viable embryo from a group for transfer from the laboratory to the womb, the researchers said.

"One of the major stumbling blocks to worldwide acceptance of a single embryo transfer policy is the lack of highly predictive criteria to select the single most viable embryo within a cohort," co-author Dr. Gayle Jones, senior research scientist at the Monash Immunology and Stem Cell Laboratories, said in a prepared statement. "The ability to use objective, measurable criteria rather than subjective observations, such as morphology, should improve the predictive value and provide sufficient confidence for clinicians to shift towards single embryo transfers for all patients without a concomitant drop in pregnancy rates. This would effectively reduce multiple pregnancies, which is a priority in the field of assisted reproductive medicine at present."

More work needs to be undertaken before these findings become applicable in the clinic, the researchers said.

More information

The American Society for Reproductive Medicine has more about infertility.

-- Kevin McKeever

SOURCE: European Society for Human Reproduction and Embryology, news release, May 13, 2008

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