Utilization and success rates of unstimulated in vitro fertilization in the United States: an analysis of the Society for Assisted Reproductive Technology database.

OBJECTIVE To examine the utilization and outcomes of natural cycle (unstimulated) IVF as reported to the Society of Assisted Reproductive Technology (SART) in 2006 and 2007. DESIGN Retrospective analysis. SETTING Dataset analysis from the SART Clinical Outcome Reporting System national database. PATIENT(S) All patients undergoing IVF as reported to SART in 2006 and 2007. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Utilization of unstimulated IVF; description of patient demographics; and comparison of implantation and pregnancy rates between unstimulated and stimulated IVF cycles. RESULT(S) During 2006 and 2007 a total of 795 unstimulated IVF cycles were initiated. Success rates were age dependent, with patients <35 years of age demonstrating clinical pregnancy rates per cycle start, retrieval, and transfer of 19.2%, 26.8%, and 35.9%, respectively. Implantation rates were statistically higher for unstimulated compared with stimulated IVF in patients who were 35 to 42 years old. CONCLUSION(S) Unstimulated IVF represents <1% of the total IVF cycles initiated in the United States. The pregnancy and live birth rates per initiated cycle were 19.2% and 15.2%, respectively, in patients <35 years old. The implantation rates in unstimulated IVF cycles compared favorably to stimulated IVF. Natural cycle IVF may be considered in a wide range of patients as an alternative therapy for the infertile couple.