Study Finds That for Women Over 40, In Vitro Fertilization Doesn't Restore Youthful Fertility
Thursday, January 15, 2009
In vitro fertilization, which thousands of women undergo each year in the hope that it will give them the same odds of having a baby as when they were younger, cannot fully turn back the biological clock, researchers are reporting today.
A study involving more than 6,000 women who underwent the treatment at a large Boston clinic found that while it could give infertile women younger than 35 about the same chance of having a baby as women typically have at that age, it could not counteract the decline in fertility that occurs among those older than 40. The study is the largest of its kind to assess the chances that women of various ages undergoing in vitro fertilization (IVF) will go home with a baby.
"Even as effective as IVF is, it can't reverse the effects of aging," said Alan S. Penzias of Harvard Medical School, who led the study, published in the New England Journal of Medicine. "We cannot reverse the biological clock."
Infertility clinics have generally reported their success rates in terms of the percentage of patients who achieve a pregnancy in each cycle of treatment, but that formulation does not address the bottom line: What are a woman's chances of having a baby after a full course of multiple treatment cycles? The new study indicates that the answer depends heavily on the woman's age.
In addition to providing women with a more accurate estimate of their chances of having a baby through IVF, Penzias said, he hopes the study will help dispel common misconceptions about women's fertility.
"One of the sad states of affairs is that there are many women who are not aware that there is an effect of aging," Penzias said. "Women feel otherwise healthy. They may be able to run the Boston Marathon. They may be at the peak of their career. When an older celebrity announces she is pregnant they may say, 'I can be like that.' But meanwhile, their fertility is potentially slowly ebbing away year by year. Even as effective as IVF is, it can't fully reverse that."
More than 113,000 IVF treatment cycles are performed each year in the United States, and the number has been increasing steadily, in part because of women delaying childbearing for their careers or for other reasons. About 10 percent of IVF cycles are done on women age 40 and older.
The Washington area has long been a large market for IVF services because of its high proportion of career-oriented professionals.
The procedure, which costs about $12,000 per attempt, can be physically and emotionally grueling. Women undergo several weeks of hormone injections to stimulate their ovaries and a sometimes-painful surgical procedure to remove their eggs, which are fertilized in a laboratory to try to create viable embryos. If that works, embryos are then transferred into the woman's womb in the hope that at least one will produce a live baby. The process often requires several cycles, with patients enduring an emotional roller coaster.
"What patients want to know is, what is their chance their IVF treatment is going to result in a baby?" said Beth A. Malizia, who helped conduct the study. "That's the answer they want, and we tried to conduct a study to give them that."
While previous studies have tried to give more accurate assessments, the new study is by far the largest and the first to examine a broad population of women, including older women and those who used both fresh and frozen embryos, Penzias said.
The researchers studied 6,164 patients who underwent 14,248 cycles at the Boston IVF clinic between 2000 and 2005. Overall, the cumulative live-birth rate after six cycles was 72 percent, based on the most optimistic analysis, which assumed that patients who did not return for follow-up IVF cycles would have the same chance of a live birth as those who continued treatment. By a more conservative analysis, which assumed no live births among those who did not return, the success rate was 51 percent. Penzias said the true rate is probably between those two figures.