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Live-Birth Rate as a Measure of IVF Success

Cumulative live-birth rate could be a practical means of evaluating potential for a live birth across multiple cycles.

In vitro fertilization (IVF) databases often cite pregnancies per cycle as an indicator of clinical success. However, this marker might not help patients evaluate the potential for a live birth across multiple cycles. In a retrospective cohort study that involved 6164 patients who underwent their first fresh-embryo IVF cycles at a single practice (>14,000 IVF cycles), investigators evaluated an alternative assessment that could provide IVF patients with a more useful measure of their chances for pregnancy. The primary outcome was the delivery of 1 live infants in 6 cycles. An "optimistic" live-birth rate was calculated based on the assumption that patients who did not return for subsequent IVF cycles had the same probability of pregnancies that resulted in live births as did patients who continued treatment; a "conservative" live-birth rate was calculated based on the assumption that patients who did not return for treatment had no live births.

The overall cumulative live-birth rate after 6 cycles was estimated to be 72% with the optimistic method and 51% with the conservative method. Stratification of results by age showed that, among patients who were <35 at the time of their first cycles, the optimistic and conservative live-birth rates were 86% and 65%, respectively. Women who were 40 had optimistic and conservative live-birth rates of only 42% and 23%.

Comment: The authors note that the true live-birth rate probably fell between the optimistic and conservative estimates. Nonetheless, this outcome measure allows patients to assess their chances for live births across multiple IVF cycles. The large sample size supports previous findings of diminishing fertility with a woman’s advancing age despite assisted reproductive treatment. However, because the data are practice-specific and the study excluded common interventions (such as donor oocytes or surrogacy), the results might have limited applicability. Nevertheless, the investigators’ proposition that cumulative live-birth rates offer a more practical estimate of IVF patients’ chances of live births deserves attention.

— Sandra Ann Carson, MD

Published in Journal Watch Women's Health January 14, 2009

Citation(s):

Malizia BA et al. Cumulative live-birth rates after in vitro fertilization. N Engl J Med 2009 Jan 15; 360:236.

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