Thirty-five pregnancies were inadvertently conceived during the midluteal application of the long-acting gonadotropin-releasing hormone agonist triptorelin acetate before ovarian stimulation for in vitro fertilization. Most of the conceptions occurred before the first or second IVF trial, and were associated with a significantly increased tendency to develop gestational diabetes. No increase in pregnancy wastage or appearance of congenital malformations occurred. Thirty-five pregnancies were inadvertently conceived during the midluteal application of the long-acting gonadotropin-releasing hormone agonist triptorelin acetate before ovarian stimulation for in vitro fertilization. Most of the conceptions occurred before the first or second IVF trial, and were associated with a significantly increased tendency to develop gestational diabetes. No increase in pregnancy wastage or appearance of congenital malformations occurred.