Yale University investigators have discovered a way to assess the odds that any one embryo will ended up in a successful pregnancy and birth. Using a non-invasive nuclear magnetic resonance form of spectroscopy called proton NMR, they were able to determine the metabolic profiles of embryos, separating those likely to result in pregnancy from those unlikely to result in pregnancy.

The finding could make a big impact on the number of multiple pregnancies now experienced by women undergoing IVF because today doctors usually implant multiple embryos in the hopes at least one will result in a pregnancy. Right now, the odds are not in the favor of pregnancy, as an average of about three embryos are usually implanted, but only about 34 percent result in pregnancy. However, among those 34 percent, 29 percent end up in multiple births, which puts the infants at higher risk for prematurity and the problems associated with it.

If this new technique proves successful in a larger study, it could help doctors find the right embryos to implant, reducing the number needed for any one IVF procedure. That could mean more pregnancies with fewer multiple births.

"The main reason for multiple gestations following in-vitro fertilization is the inability to precisely estimate the reproductive potential of individual embryos," writes study author Emre Seli, M.D. "We found that proton NMR ... will determine the metabolic profile of the embryo and accurately predict its reproductive potential."

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SOURCE: The Society for Gynecologic Investigation Conference in Reno, March 14-17, 2007