In a report presented at the European Society of Human Reproduction and Embryology, researchers provided some much-needed information that they hope will help couples using IVF to make more informed decisions about how best to use the reproductive technology.
Infertility increases with age, and while there are many reasons why couples have a hard time conceiving, one important contribution is the quality of the woman’s eggs. Because women are born with all of the eggs they use throughout their lifetime, the older the eggs are, the more vulnerable they are to developing genetic and other abnormalities that make them weaker candidates for getting fertilized by sperm and developing into a healthy baby.
But at what age does this process truly decline? Most reproductive data shows that live birth rates start to decline when the woman reaches 35, so Dr. Marta Devesa from the department of obstetrics and gynecology at Women’s Health Dexeus in Barcelona, Spain and her colleagues decided to analyze birth rates by age and whether women used fresh or frozen embryos in their IVF cycle. They found that the cumulative live birth rate—which includes every transfer of an embryo from a single stimulation cycle (most women produce multiple eggs and many of these are fertilized to become embryos, one of which is usually transferred to the womb and the rest of which are frozen for future transfer)—dropped with age.
But they also learned that the live birth rate was really driven by the first transfer of the fresh embryo, and wasn’t significantly increased by transferring additional frozen embryos if the first transfer didn’t result in a pregnancy. In other words, the first, fresh embryo provides the best chance for pregnancy, particularly in women age 42 or older. “The benefit from the frozen embryos is very limited,” says Devesa.
The findings don’t suggest that freezing embryos isn’t worth the effort or the cost, however. For women ages 38-39, the extra benefit from transferring frozen embryos a live birth was 13%; for women ages 40-41, 9%, and for women 42-43, 2%. For women 42 years or older, the frozen embryos only added a 1% increased chance of a live birth. For them, their chances of pregnancy may be higher with a donor egg.
The number of embryos may also be an indicator of a couple’s chances of having a baby. “If we have more embryos to freeze, the live birth rate from the fresh embryo is significantly higher than if we didn’t have any embryos to freeze,” she says. “Why? Because more embryos means we have a better chance of selecting the best embryo.”
The findings, she hopes, will help doctors and patients to better assess their chances of pregnancy and provide more accurate information for couples about whether they should continue with IVF using their own eggs and sperm and when they should consider using donor eggs. While each couple decides on how they want to proceed with IVF, with the current findings, “at least we can give them real expectations about their chances of a live birth, so they can manage their expectations correctly and properly,” Devesa says.