Predicting In Vitro Fertilzation (IVF) Success

In Vitro Fertilization (IVF) was used successfully for the first time in the United States in 1981. Since then, more than 250,000 babies have been born as a result of using the IVF technique. The procedure is expensive, costing in the neighborhood of $10,000 per attempt, and the chance of success is impossible to predict. This leaves couples at a disadvantage when trying to decide whether to give up or to continue when previous IVF cycles have failed. But researchers have uncovered four factors that they say can predict pregnancy with an accuracy of 70 percent.

IVF is a method of assisted reproduction, where a man's sperm and a woman's egg are combined in a laboratory dish, where fertilization occurs. The resulting embryo is then transferred to the woman's uterus to implant and develop naturally. Each attempt is called a cycle. Typically, each IVF cycle produces five to 12 embryos. Usually, two to four embryos are chosen and placed in the woman's uterus at one time. Doctors focus on "good embryos" and choose those that appear to be growing more vigorously than others. But the study by researchers at Stanford University indicates doctors should take the quality of the entire batch of embryos into account in order to have the entire picture of a woman's chances of getting pregnant.

The researchers examined 665 cycles of IVF in women under age 45 that took place at Stanford in 2005. When analyzing the 4,144 embryos that were produced during the cycles, the researchers looked at about 30 factors that could affect IVF success, and then narrowed them down to the four most powerful: the total number of embryos that a couple produces during a cycle, the number of embryos that survive to the eight-cell stage, the percentage of embryos that stop dividing, and a woman's level of follicle-stimulating hormone. Dr. Mylene Yao, professor of obstetrics and gynecology at Stanford University and lead author of the study, says these four factors indirectly reflect all the other elements that play a role in a couple's fertility, including a woman's age and her medical history. "It's extremely interesting that the four factors do not actually relate to the embryos that are transferred to the womb. So while it's still important to identify the best embryos for transfer, this suggests that we shouldn't neglect all the other embryos and the information that we can extract from them."

Dr. Yao says she hopes that knowing these factors will someday help doctors to counsel patients who are trying to decide whether they want to commit to an IVF cycle or not. "People make decisions based on probability," Dr. Yao said. "At that point, it's really important to give a more accurate prediction." She notes that more research is needed before this new method can be adopted by doctors. Her team is already working on a larger, more comprehensive follow-up study that involves four years of data and uses live birth, rather than a positive pregnancy test, as the outcome.

The study was published in the July 2 issue of Public Library of Science-ONE (PLos ONE).