DEFINING AND INTERPRETING PREGNANCY SUCCESS RATES FOR IN-VITRO FERTILIZATION

Objectives: To review current practice in describing pregnancy success rates after IVF-ET, to identify issues associated with interpreting t hese rates, and to suggest useful methods of describing these rates in the future. Design: Review of literature concerning medical, epidemio logic, and statistical aspects of reporting IVF-ET pregnancy success r ates. Setting: The United States. Patients: Infertile couples particip ating in IVF-ET. Main Outcome Measures: Usefulness and accuracy of IVF -ET pregnancy reporting. Results: Several groups have collected inform ation on the pregnancy success rates of IVF-ET clinics and have discus sed appropriate definitions of pregnancy success. The largest of these groups in the United States is The American Fertility Society and its affiliate, the Society for Assisted Reproductive Technology. The numb er of live deliveries per 100 ET procedures and the number of live del iveries per 100 egg retrieval procedures are among the most commonly u sed definitions. Conclusion: The most commonly used definitions are pa rticularly useful for describing the probability that a live infant wi ll be delivered after IVF-ET is completed. To measure the effectivenes s of the IVF-ET procedures and the costs of undergoing IVF-ET, other d efinitions are also important. Success rates need to be stratified by patient characteristics, such as age, that affect the probability of s uccess.