Description of fertility and prognosis of patients with borderline ovarian tumor (BOT) treated by fertility-sparing surgery through a longitudinal study from the French national cancer network.All consecutive patients diagnosed with BOT from the French National Network dedicated to Ovarian Malignant Rare Tumors from 2010 and 2017 were selected. In 2018, an update was made by sending a questionnaire regarding recurrence and fertility to patients aged under 43 years at diagnosis and treated conservatively. We compared the characteristics of the patients with/without recurrence and with/without live birth.Fifty-two patients aged 18 to 42 years presented a desire of pregnancy. Thirty patients (58%) presented a FIGO IA tumor, and 20 patients were treated by bilateral cystectomies (38%). We observed at least one live birth for 33 patients (63%) and local recurrences in 20 patients (38%). Both recurrence and live birth in 17 patients (33%) were reported, with recurrence occurring before pregnancy, after a second fertility-sparing treatment, in half of the cases. No factors associated with recurrence or live birth in this study were identified. Moreover, in this population, both recurrence and live birth were independent of age, with a linear risk along time. Disease-free survival was worse for patients treated with bilateral cystectomy (n = 20, 38%), with no difference in terms of fertility.Two third of the patients experienced life birth after conservation surgery. We did not highlight an age/time from surgery for which the risk of recurrence outweighs the chance of pregnancy and to radicalize surgery. Moreover, almost a quarter of the live birth occurred after recurrence, with no more further event to date in these patients. The results encourage to consider a second fertility-sparing surgery after local borderline recurrence in the case of pregnancy desire. All these decisions must be discussed in specialized multidisciplinary boards.