Elective and Onco-fertility preservation: factors related to IVF outcomes

STUDY QUESTION: Is the indication for fertility preservation (FP) related to success in IVF cycles after elective-FP (EFP) for age-related fertility decline and FP before cancer treatment (Onco-FP)? SUMMARY ANSWER: Although success rates were lower in cancer patients, there was no statistically significant association between malignant disease and reproductive outcome after correction for age and controlled-ovarian stimulation (COS) regime. WHAT IS KNOWN ALREADY: FP is increasingly applied in assisted reproduction, but little is known about the outcome of IVF cycles with vitrified oocytes in FP patients. STUDY DESIGN, SIZE, DURATION: Retrospective, observational multicenter study of vitrification cycles for FP and of the warming cycles of women who returned to attempt pregnancy from January 2007 to May 2018. PARTICIPANTS/MATERIALS, SETTING, METHODS: In all, 6362 women (EFP = 5289 patients; 7044 cycles + Onco-FP = 1073 patients; 1172 cycles) had their oocytes vitrified for FP. A logistic regression analysis was performed to examine the impact of indication for FP corrected for age at vitrification. The protocol used for COS was also included as a possible confounder. The main outcome measures were oocyte survival and live birth. A detailed description of the baseline and clinical data is provided, with comparisons between EFP and Onco-FP. The cumulative live birth rate (CLBR) per utilized oocyte according to age at vitrification was analyzed in those patients returning to use their oocytes. MAIN RESULTS AND ROLE OF CHANCE: Age at vitrification was significantly older in EFP patients (37.2 +/- 4.9 vs. 32.3 +/- 3.5 year; P < 0.0001). Fewer oocytes were retrieved and vitrified per cycle in EFP (9.6 +/- 8.4 vs. 11.4 +/- 3.5 and 7.3 +/- 11.3 vs. 8.7 +/- 2.1, respectively; P < 0.05), but numbers became comparable when analyzed per patient (12.8 +/- 7.4 vs. 12.5 +/- 3.2 and 9.8 +/- 6.4 vs. 9.5 +/- 2.6). Storage time was shorter in EFP (2.1 +/- 1.6 vs. 4.1 +/- 0.9 years; P < 0.0001). In all, 641 (12.1%) EFP and 80 (7.4%) Onco-FP patients returned to attempt pregnancy (P < 0.05). Overall oocyte survival was comparable (83.9% vs. 81.8%; NS), but lower for onco-FP patients among younger (= 35 year) subjects (81.2% vs. 91.4%; P > 0.05). Fewer EFP cycles finished in embryo transfer (50.2% vs. 72.5%) (P < 0.05). The implantation rate was 42.6% and 32.5% in EFP versus Onco-FP (P < 0.05). Ongoing pregnancy (57.7% vs. 35.7%) and live birth rates (68.8% vs. 41.1%) were higher in EFP patients aged = 35 than the Onco-FP matching age patients (P < 0.05). The reason for FP per se had no effect on oocyte survival (OR = 1.484 [95% CI = 0.876-2.252]; P = 0.202) or the CLBR (OR = 1.275 [95% CI = 0.711-2.284]; P = 0.414). Conversely, age (< 36 vs. = 36 y) impacted oocyte survival (adj. OR = 1.922 [95% CI = 1.274-2.900]; P = 0.025) and the CLBR (adj. OR=3.106 [95% CI = 2.039-4.733]; P < 0.0001). The Kaplan-Meier analysis showed a significantly higher cumulative probability of live birth in patients < 36 versus > 36 in EFP (P < 0.0001), with improved outcomes when more oocytes were available for IVF. LIMITATIONS, REASONS FOR CAUTION: Statistical power to compare IVF outcomes is limited by the few women who came to use their oocytes in the Onco-FP group. The patients' ages and the COS protocols used were significantly different between the EFP and ONCO-PP groups. WIDER IMPLICATIONS OF THE FINDINGS: Although the implantation rate was significantly lower in the Onco-FP patients the impact of cancer disease per se was not proven'. EFP patients should be counseled according to their age and number of available oocytes. STUDY FUNDING/COMPETING INTEREST(S): No external funding was used for this study. The authors have no conflicts of interest.