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| |  Researchers Identify Predictive Factors for Successful IVF STANFORD, Calif. -- July 1, 2008 -- Researchers have identified a method that can predict with 70% accuracy whether a woman undergoing in vitro fertilisation (IVF) treatment will become pregnant, according to a study that will appear in the July 2 issue of Public Library of Science-ONE. The new method involves using 4 factors to determine a woman's chance of becoming pregnant from an IVF cycle. These variables may prove "critical in counselling patients, improving treatment, and ultimately in developing ... more customised treatments," the authors wrote. Although physicians look at many factors such as the age of the woman, levels of certain hormones, the quality of her eggs, and individual characteristics of each embryo, to help predict the likelihood that the patient will become pregnant, there isn't a consistently accurate test yet to determine whether an individual woman will have success with IVF. "The information isn't yet customised to the individual patient," said lead author Mylene Yao, MD, Stanford University School of Medicine, Stanford, California. "And what patients really want to know is: 'What is my chance of getting pregnant?' " Nationwide, the percentage of IVF cycles that result in pregnancy for women using their own eggs ranges from about 18% to 45%, depending on age and other factors, according to the Society for Assisted Reproductive Technology. Dr. Yao and colleagues analysed clinical data from 665 IVF cycles performed at Stanford in 2005. They looked at 30 variables (on patient characteristics, clinical diagnoses, treatment protocol, and embryo characteristics) and examined the association of each variable with IVF outcomes, as defined by results of a pregnancy test. The researchers found that 4 factors -- total number of embryos, number of 8-cell embryos, percentage of embryos that stopped dividing and would die, and the woman's follicle-stimulating hormone level -- were most important in determining a woman's chance of becoming pregnant. The 4 factors were 70% accurate in predicting whether the current IVF cycle would result in a pregnancy. The researchers also found that these 4 factors were more predictive than any single measure of the actual transferred embryo(s). An individual embryo could meet all the criteria for a transfer, but if the IVF cycle produced a small number of embryos, few 8-cell embryos, and a high percentage of embryos that stopped dividing, the woman's chance of getting pregnant could actually be quite low. Dr. Yao said she hopes the method of using these factors will someday help doctors counsel those patients trying to decide whether to go for another IVF cycle. IVF is expensive, both financially and emotionally, and she suspects many couples would embrace information that would better inform their decision. "People make decisions based on probability," Dr. Yao said. "At that point, it's really important to give a more accurate prediction." More information is needed before clinicians adopt the new method. Dr. Yao and colleagues are now analysing results from a follow-up study. The larger, more comprehensive study involves 4 years of data and uses live birth, rather than a positive pregnancy test, as the outcome. SOURCE: Stanford University Medical Center
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