Spontaneous conception after the birth of infants conceived through in vitro fertilization treatment

OBJECTIVE: To investigate the incidence of spontaneous conception after the birth of infants conceived through IVF in couples with subfertility caused by endometriosis, a mild male factor, or unexplained factors, and to identify clinical conditions related to the occurrence of spontaneous conception. DESIGN: Retrospective analysis. SETTING: Department of Obstetrics and Gynecology, Akita University School of Medicine, Akita, Japan. PATIENT(S): One hundred forty-two women who conceived through IVF and 25 of the 142 women who subsequently conceived spontaneously. INTERVENTION(S): Patient characteristics and IVF data were obtained from hospital records, and follow-up data were collected through telephone interviews. MAIN OUTCOME MEASURE(S): Cumulative conception rate. RESULT(S): The cumulative conception rate at 60 months after the delivery of infants conceived through IVF was 18%, with most conceptions occurring within 2 years of delivery. Proportional hazard analysis indicated that patient age was the most important clinical variable related to the occurrence of spontaneous conception. CONCLUSION(S): This study provides information that will be useful in counseling subfertile couples who have conceived through the use of IVF.