Objective: To determine what percentage of embryos achieved through assisted reproductive technology (ART) do not result in a live birth and to examine the relationships among the number of embryos transferred, infants delivered, and embryos wasted.
Design: Retrospective correlational study of the U.S. summary data of ART results for the years of 1995-2001.
Patients: Fertility clinics reporting data to the Society of Assisted Reproductive Technology (SART).
Intervention(s): None.
Main outcome measure(s): Statistics for ART cycles using fresh, nondonor eggs and embryos were derived, and the percentage of embryos wasted each year was calculated. Trends over time were evaluated for percent embryos wasted, the average number of embryos transferred, and the delivery per transfer rate. Correlations between these variables were analyzed.
Result(s): The percentage of embryos transferred that did not produce a live birth was 90.8 in 1995 and decreased to 84.9 in 2001. This trend significantly correlated with a reduction in the number of embryos transferred (from 3.9 to 3.1) and with an improvement in delivery rate per transfer (25% to 33.4%).
Conclusion(s): The vast majority of embryos produced in vitro and transferred fail to develop into an infant, supporting the concept that only a small fraction of embryos has the capacity to become a live birth. Clinicians should strive to reduce embryonic wastage without an adverse effect on delivery rates by perfecting methods of ovarian stimulation and embryo screening, and by transferring fewer embryos.