In vitro fertilization in unstimulated cycles: the University of Southern California experience.

OBJECTIVE

To describe the clinical experience of our center with in vitro fertilization (IVF) in unstimulated cycles and to provide a comparison to stimulated cycles.

DESIGN

Spontaneous ovulatory cycles were triggered with human chorionic gonadotropin in the midcycle, and 78 aspirations for IVF were performed, with the remainder of the IVF cycle proceeding in a standard manner.

SETTING

The IVF program of the University of Southern California and the California Medical Center, Los Angeles, California.

PATIENTS

Spontaneously ovulatory women (n = 46) with predominantly pelvic factor as their principal cause of infertility, under the age of 40, and no male factor.

INTERVENTIONS

Human chorionic gonadotropin administration in midcycle, follicle aspiration, IVF, and embryo transfer.

MAIN OUTCOME MEASURES

Embryo implantation and pregnancy.

RESULTS

Seventy-eight follicle aspirations resulted in 11 clinical (14%) and 9 ongoing (12%) pregnancies. The per embryo implantation rate was 13% clinical and 11% ongoing. There was no decrease in per cycle pregnancy rates (PRs) for up to three unstimulated cycles.

CONCLUSIONS

Unstimulated IVF is a viable alternative to stimulated cycles with PRs approximately one half those of stimulated cycles. It is reasonable to offer patients up to three cycles of unstimulated IVF without expecting a decrease in PRs.