STUDY QUESTION

Does luteal estradiol (E2) pretreatment give a similar number of retrieved oocytes compared to no-pretreatment in advanced-aged women stimulated with corifollitropin alfa in an antagonist protocol?

SUMMARY ANSWER

Programming antagonist cycles with luteal E2 gave similar number of retrieved oocytes compared to no-pretreatment in women aged 38-42 years.

WHAT IS KNOWN ALREADY

Programming antagonist cycles with luteal E2 pretreatment is a valuable tool to organize the IVF procedure better and is safe without any known impact on cycle outcome. However, variable effects were observed on the number of retrieved oocytes depending on the treated population. In advanced-age women, recruitable follicles tend to decrease in number and to be more heterogeneous in size but it remains unclear if estradiol pretreatment could change the oocyte yield through its negative feed-back effect on FSH intercycle rise.

STUDY DESIGN, SIZE, DURATION: This non-blinded randomized controlled non-inferiority trial was conducted between 2016 and 2022 with centrally computerized randomization and concealed allocation. Participants were 324 women aged 38-42 years undergoing IVF treatment. The primary endpoint was the total number of retrieved oocytes. Statistical analysis was performed with one-sided alpha risk of 2.5% and 95% confidence interval (CI) with the non-inferiority of E2 pretreatment proved by a P value <0.025 and a lower delta margin of the CI within two oocytes compared to no pretreatment. Secondary endpoints were duration and total dosage of recombinant FSH, cancellation rate, percentage of oocyte pick-up (OPU) on working days, total number of metaphase II oocytes and obtained embryos, fresh transfer live birth rate, and cumulative live birth rate.

PARTICIPANTS/MATERIALS, SETTING, METHODS: This multicentric study enrolled women with regular cycles, weight >50 kg and body mass index <32, IVF cycle 1-2. According to randomization, micronized estradiol 2 mg twice a day was started on days 20-24 and continued until Wednesday beyond the onset of menses followed by administration of corifollitropin alfa on Friday, i.e. stimulation (S)1 or from D1-3 of a natural cycle in unpretreated patients. GnRH antagonist was started at S6 and additional FSH at S8.

MAIN RESULTS AND THE ROLE OF CHANCE

Basal characteristics were similar in patients randomized in E2 pretreated (n = 164) and non-pretreated (n = 160) groups (intended to treat (ITT) population). A total of 291 patients started treatment (per protocol (PP) population), 147 in E2 pretreated group with a mean number [SD] of pre-treatment days 9.8 [2.6] and 144 in the non-pretreated group. Despite advanced age, oocyte yields ranged from 0 to 29 in both groups with a median number of 6 retrieved oocytes in accordance with a mean anti-Müllerian hormone (AMH) level above 1.2 ng/ml. We demonstrated the non-inferiority of E2 pretreatment with a mean difference of -0.1 oocyte 95% CI [-1.5; 1.3] P = 0.004 in the PP population and a mean difference of -0.44 oocyte [-1.84; 0.97] P = 0.014 in the ITT population. Oocyte retrieval was more often on working days in E2 pretreated patients (91.9 versus 74.2%, P < 0.001). In patients reaching OPU, the duration of stimulation was statistically significantly longer (11.7 [1.7] versus 10.8 [1.8] days, P < 0.001) and the extra FSH dosage in addition to corifollitropin alfa was statistically significantly higher (1040 [548] versus 778 [504] IU, P < 0.001) in E2 pretreated than non-pretreated patients. We did not observe any significant differences in the number of retrieved oocytes (8.4 [6.1] versus 9.1 [6.0]), in the number of Metaphase 2 oocytes (7 [5.5] versus 7.3 [5.2]) nor in the number of obtained embryos (5 [4.6] versus 5.2 [4.2]) in E2 pretreated patients compared to non-pretreated patients. The live birth rate after fresh transfer (16.2% versus 18.5%, respectively), and the cumulative live birth rate per patient (17.7% versus 22.9%, respectively) were similar in both groups. Among the PP population, 31.6% of patients fulfilled the criteria for group 4 of Poseïdon classification (AMH <1.2 ng/ml and/or antral follicle count <5). In this sub-group of patients, we observed in contrast a statistically higher number of retrieved oocytes in E2 pretreated patients compared to non-pretreated (5.1 [3.8] versus 3.4 [2.7], respectively, the mean difference of +1.7 oocyte [0.2; 3.2] P = 0.022) but without significant difference in the cumulative live birth rate per patient (15.7% versus 7.3%, respectively).

LIMITATIONS, REASONS FOR CAUTION: Our stimulated women older than 38 years obtained a wide range of collected oocytes suggesting very different stages of ovarian aging in both groups. E2 pretreatment is more likely to increase oocyte yield at the stage of ovarian aging characterized by asynchrony of a reduced follicular cohort. Another limitation is the sample size in sub-group analysis of patients with AMH <1.2 ng/ml. Finally, the absence of placebo for pretreatment could also introduce possible bias.

WIDER IMPLICATIONS OF THE FINDINGS

Programming antagonist cycles with luteal E2 pretreatment seems a useful tool in advanced age women to better schedule oocyte retrievals on working days. However, the potential benefit of the number of collected oocytes remains to be demonstrated in a larger population displaying the characteristics of decreased ovarian reserve encountered in Poseïdon classification.

STUDY FUNDING/COMPETING INTEREST(S): Research grant from (MSD) Organon, France. I.C., S.D., B.B., X.M., S.G., and C.J. have no conflict of interest with this study. I.C.D. declares fees as speaker from Merck KGaA, Gedeon Richter, MSD (Organon, France), Ferring, Theramex, and IBSA and participation on advisory board from Merck KGaA. I.C.D. also declares consulting fees, and travel and meeting support from Merck KGaA. N.M. declares grants paid to their institution from MSD (Organon, France); consulting fees from MSD (Organon, France), Ferring, and Merck KGaA; honoraria from Merck KGaA, General Electrics, Genevrier (IBSA Pharma), and Theramex; support for travel and meetings from Theramex, Merck KGaG, and Gedeon Richter; and equipment paid to their institution from Goodlife Pharma. N.C. declares grants from IBSA Pharma, Merck KGaA, Ferring, and Gedeon Richter; support for travel and meetings from IBSA Pharma, Merck KGaG, MSD (Organon, France), Gedeon Richter, and Theramex; and participation on advisory board from Merck KGaA. A.G.L. declares fees as speaker from Merck KGaA, Gedeon Richter, MSD (Organon, France), Ferring, Theramex, and IBSA.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT02884245.

TRIAL REGISTRATION DATE

29 August 2016.

DATE OF FIRST PATIENT’S ENROLMENT: 4 November 2016.