IVF More Successful in Younger Women Than Older Women

Alice Goodman

January 14, 2009

January 14, 2009 — Women who undergo up to 6 cycles of in vitro fertilization (IVF) with either fresh or frozen nondonor embryos are more likely to achieve a live birth if they are younger, according to a large, retrospective, single-center study published in the January 15 issue of the New England Journal of Medicine.

"Our results indicate that IVF may largely overcome infertility in younger women, but it does not reverse the age-dependent decline in fertility," write Beth A. Malizia, MD, and colleagues at Beth Israel Deaconess Medical Center and Harvard Medical School in Boston, Massachusetts.

The retrospective cohort study included 6164 patients undergoing 14,248 IVF cycles. Cumulative birth rates were estimated using both an "optimistic" method (assuming that women who did not return for subsequent IVF cycles had the same chance of having a live birth as those who did return) and a "conservative" method (assuming that women who did not return for subsequent IVF treatment had no chance of having a live birth). After 6 IVF cycles, the cumulative live-birth rate was 72% with the optimistic analysis and 51% with the conservative analysis. Among the cohort of women aged 35 years and younger, the corresponding rates were 86% and 65%. For women aged 40 years or older, the corresponding rates were 42% and 23%.

The authors note that the optimistic rates probably represent an overestimate, while the conservative rates are possibly overly pessimistic. "Thus, the true cumulative live-birth rate in our population was probably between the conservative and optimistic estimate," they write.

The age-specific results of this study are more generalizable than results of previous studies of IVF, which were either not stratified according to age or included small sample sizes. The present study included a large number of patients in each age group undergoing 6 IVF cycles, and the authors believe that the "specific cumulative live-birth rates...can be used to counsel patients of any age." The present study overcomes limitations of previous studies that used pregnancy (rather than live birth) as the primary outcome and did not report multiple births.

The rates of pregnancy and live births per cycle reported in this study are slightly lower than those reported in 2005 national data. The authors suggest that the lower rates may reflect insurance coverage in the state of Massachusetts, which encourages the transfer of fewer embryos, thereby potentially reducing the number of multiple live births.

"These age-specific optimistic and conservative cumulative live-birth rates can facilitate individual counseling in a large population of patients considering IVF treatment," the authors conclude.

N Engl J Med. 2009;360:236–243.


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