That’s the question that many women, couples, and fertility doctors have debated. The stress, expense, and inconvenience of a round of in vitro fertilization (IVF) make it tempting to transfer two embryos, hoping that at least one will result in a healthy baby – but with more and more data showing the serious risks of multiples to moms and babies, that’s often far from a clear-cut decision.
Now researchers in Sweden may have helped make that tough decision a little easier to make. As reported at the annual meeting of the European Society for Human Reproduction in Stockholm earlier this month, the scientists have come up with what they say is a reliable way to decide whether one or two embryos should be transferred without lowering the live birth rate, said Dr. Jan Holte at the meeting.
Dr. Holte and his co-authors looked at over 3,000 embryo transfers from 1999 to 2002 and noted 80 different factors that can influence the success of fertility treatment. Four in particular stood out: embryo quality; a woman’s age; number of eggs retrieved; and information about a woman’s past IVF attempts. Crunching those numbers, the researchers could predict the chances of pregnancy from a single or double embryo transfer and also the risk of twins. They tested their model in 3,410 transfers between 2004 and 2007, aiming to keep the twin rate to no more than 15 percent.
When they applied their model to these transfers the number of single embryo transfers went up to 76 percent – and the rate of twins dropped from 26% to under 2%, though the live birth rates were very similar, at about 31%, and higher in some cases. Just as exciting: Average birth weights in these infants were higher and premature births and low birthweight dropped by two-thirds. “These improved outcomes were entirely due to the lower rate of twins,” said Dr. Holte in a press release. To date, four clinics in Europe are using the new predictor. Here's hoping US clinics consider it as well.