Sperm cryopreservation does not affect live birth rate in normozoospermic men: analysis of 7969 oocyte donation cycles.

STUDY QUESTION: Does sperm cryopreservation influence the reproductive outcomes of normozoospermic patients in oocyte donation cycles? SUMMARY ANSWER: After controlling for confounders, the use of cryopreserved semen from normozoospermic patients does not affect pregnancy and live birth rates after elective ICSI. WHAT IS KNOWN ALREADY: Sperm cryopreservation by slow freezing is a common practice in ART. While frozen-thawed semen typically presents reduced motility and vitality, its use for ICSI is generally considered adequate in terms of reproductive outcomes. Nevertheless, most studies comparing reproductive outcomes between fresh and cryopreserved sperm include patients with severe male factor (testicular sperm, oligo-, and/or asthenozoospermia) or women of advanced maternal age, where the altered quality of the gametes can partially mask the full effect of freezing/thawing. STUDY DESIGN, SIZE, DURATION: The study included a retrospective cohort of 7969 couples undergoing their first oocyte donation cycle between January 2013 and December 2019 in one large clinic, using normozoospermic semen from the male partner. All cycles involved elective ICSI, fresh oocytes, and a fresh embryo transfer, either at cleavage or blastocyst stage. Two study groups were established based on the sperm status: fresh (n = 2865) and cryopreserved (n = 5104). PARTICIPANTS/MATERIALS, SETTING, METHODS: A slow freezing protocol was used for all sperm cryopreservation. Sperm washing, capacitation, and selection prior to ICSI were performed identically for fresh and frozen-thawed samples, using pellet swim-up. Fertilization rate (FR), pregnancy (biochemical and ongoing), and live birth rates were compared between study groups using univariate and multivariate regression analyses. MAIN RESULTS AND THE ROLE OF CHANCE: Male and female age, sperm concentration and motility after ejaculation, and number of oocytes inseminated were similar between cycles using fresh or cryopreserved sperm. Analysis by Student's t-test did not indicate a significant difference in FR between fresh and cryopreserved sperm (P = 0.0591); however, after adjusting for confounders, this difference reached statistical significance: 74.65% FR for fresh (CI 95%: 73.92-75.38) versus 73.66% for cryopreserved sperm (CI 95%: 73.11-74.20), P = 0.0334. The adjusted regression analysis revealed higher odds of biochemical pregnancy when using fresh sperm (odds ratio (OR): 1.143, P = 0.0175), but no significant effects of sperm cryopreservation were observed for ongoing pregnancy (OR: 1.101, P = 0.0983) and live birth (OR: 1.082, P = 0.1805). LIMITATIONS, REASONS FOR CAUTION: Caution should be exerted when extrapolating these results to different protocols for sperm cryopreservation and selection, or to IVM, advanced maternal age and classical IVF cycles, which were excluded from analysis. Owing to the retrospective nature of the study, some uncontrolled for variables may affect the results. WIDER IMPLICATIONS OF THE FINDINGS: Sperm cryopreservation does not affect pregnancy and live birth rates in normozoospermic patients, and although it may lower FR s slightly, this would not be clinically relevant. In line with previous studies that included patients with an apparent male or female factor, sperm cryopreservation is a safe and convenient technique. STUDY FUNDING/COMPETING INTEREST(S): The study received no external funding and all authors have no conflicts of interest to declare. TRIAL REGISTRATION NUMBER: N/A.

Significant differences in efficiency between two commonly used ionophore solutions for assisted oocyte activation (AOA): a prospective comparison of ionomycin and A23187.

PURPOSE: Despite the success of ICSI in treating severe male factor infertile patients, total fertilization failure (FF) still occurs in around 1-3% of ICSI cycles. To overcome FF, the use of calcium ionophores has been proposed to induce oocyte activation and restore fertilization rates. However, assisted oocyte activation (AOA) protocols and ionophores vary between laboratories, and the morphokinetic development underlying AOA remains understudied. METHODS: A prospective single-center cohort study involving 81 in vitro matured metaphase-II oocytes from 66 oocyte donation cycles artificially activated by A23187 (GM508 CultActive, Gynemed) (n=42) or ionomycin (n=39). Parthenogenesis was induced, and morphokinetic parameters (tPNa, tPNf, t2-t8, tSB, and tB) were compared between the 2 study groups and a control group comprising 39 2PN-zygotes from standard ICSI cycles. RESULTS: Ionomycin treatment resulted in higher activation rates compared to A23187 (38.5% vs 23.8%, p=0.15). Importantly, none of the A23187-activated parthenotes formed blastocysts. When evaluating the morphokinetic dynamics between the two ionophores, we found that tPNa and tPNf were significantly delayed in the group treated by A23187 (11.84 vs 5.31, p=0.002 and 50.15 vs 29.69, p=0.005, respectively). t2 was significantly delayed in A23187-activated parthenotes when compared to the double heterologous control embryo group. In contrast, the morphokinetic development of ionomycin-activated parthenotes was comparable to control embryos (p>0.05). CONCLUSION: Our results suggest that A23187 leads to lower oocyte activation rates and profoundly affects morphokinetic timings and preimplantation development in parthenotes. Despite our limited sample size and low parthenote competence, standardization and further optimization of AOA protocols may allow wider use and improved outcomes for FF cycles.

A microfluidic sperm-sorting device reduces the proportion of sperm with double-stranded DNA fragmentation.

Sperm DNA fragmentation can be produced in one (ssSDF) or both (dsSDF) DNA strands, linked to difficulties in naturally achieving a pregnancy and recurrent miscarriages, respectively. The techniques more frequently used to select sperm require centrifugation, which may induce sperm DNA fragmentation (SDF). The objective of this study was to assess whether the microfluidic-based device FertileChip® (now ZyMot®ICSI) can diminish the proportion of sperm with dsSDF. First, in a blinded split pilot study, the semen of nine patients diagnosed with ≥60% dsSDF, was divided into three aliquots: not processed, processed with FertileChip®, and processed with swim up. The three aliquots were all analyzed using neutral COMET for the detection of dsSDF, resulting in a reduction of 46% (P < 0.001) with FertileChip® (dsSDF: 34.9%) compared with the ejaculate and the swim up (dsSDF: 65%). Thereafter, the FertileChip® was introduced into clinical practice and a cohort of 163 consecutive ICSI cycles of patients diagnosed with ≥60% dsSDF was analyzed. Fertilization rate was 75.41%. Pregnancy rates after the first embryo transfer were 53.2% (biochemical), 37.8% (clinical), 34% (ongoing) and the live birth rate was 28.8%. Cumulative pregnancy rates after one (65.4% of patients), two (27.6% of patients) or three (6.4% of patients) transfers were 66% (biochemical), 56.4% (clinical), 53.4% (ongoing) and the live birth rate was 42%. The selection of spermatozoa using Fertile Chip® significantly diminishes the percentage of dsSDF, compared with either the fresh ejaculate or after swim up. Its applicability in ICSI cycles of patients with high dsSDF resulted in good laboratory and clinical outcomes.

Undetectable viral RNA in oocytes from SARS-CoV-2 positive women.

A central concern for the safe provision of ART during the current coronavirus disease 2019 (COVID-19) pandemic is the possibility of vertical transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection through gametes and preimplantation embryos. Unfortunately, data on SARS-CoV-2 viral presence in oocytes of infected individuals are not available to date. We describe the case of two women who underwent controlled ovarian stimulation and tested positive to SARS-CoV-2 infection by PCR on the day of oocyte collection. The viral RNA for gene N was undetectable in all the oocytes analyzed from the two women.

Sperm donation: an alternative to improve post-ICSI live birth rates in advanced maternal age patients.

STUDY QUESTION: Can sperm donation increase live birth rates following ICSI in advanced maternal age (AMA) patients? SUMMARY ANSWER: Sperm donation increases the live birth rate in AMA ICSI cycles. WHAT IS KNOWN ALREADY: In ICSI practice, sperm donation has been predominantly applied to overcome male infertility. The involvement of paternal age and lower sperm quality in the severe reduction in fertility observed in AMA patients remains to be clarified. STUDY DESIGN, SIZE, DURATION: Retrospective multicenter cohort study including data generated between 2015 and 2019 from 755 ICSI cycles achieving a fresh embryo transfer, of which 337 were first homologous cycles (normozoospermic partner sperm and homologous oocytes) and 418 were first sperm donation cycles (donor sperm and homologous oocytes). The association of sperm origin (partner vs donor) with live birth was assessed by multivariate analysis in non-AMA (<37 years, n = 278) and AMA (≥37 years, n = 477) patients, separately, including in the model all variables previously found to be associated with live birth in a univariate analysis (number of MII oocytes recovered, number of embryos transferred, and maternal age). ICSI outcomes were compared between sperm donation and homologous cycles in overall, non-AMA and AMA patients. PARTICIPANTS/MATERIALS, SETTING, METHODS: The study was conducted in three fertility clinics and included 755 Caucasian patients aged 24-42 years undergoing their first homologous or sperm donation ICSI cycle achieving a fresh embryo transfer. MAIN RESULTS AND THE ROLE OF CHANCE: The multivariate analysis revealed that sperm donation was positively associated with the likelihood of a live birth independently of all other variables tested in AMA (P = 0.02), but not in non-AMA patients. Live birth, delivery, and miscarriage rates differed substantially between sperm donation and homologous AMA cycles; live birth and delivery rates were 70-75% higher (25.4% vs 14.5% and 22.5% vs 13.5%, respectively; P < 0.01), while miscarriage occurrence was less than half (18.0% vs 39.5%; P < 0.01) in sperm donation compared to homologous AMA cycles. LIMITATIONS, REASONS FOR CAUTION: This study is limited by its retrospective nature, differences in patients profiles between sperm donation and homologous-control groups and varying proportion of donor cycles between fertility centers, although these variations have been controlled for in the statistical analysis. WIDER IMPLICATIONS OF THE FINDINGS: The findings suggest that sperm donation increases live birth rates while reducing miscarriage occurrence in AMA patients, and thus may be a valid strategy to improve ICSI outcomes in this growing and challenging patient group. STUDY FUNDING/COMPETING INTEREST(S): N/A. TRIAL REGISTRATION NUMBER: N/A.

Assisted oocyte activation effects on the morphokinetic pattern of derived embryos.

OBJECTIVE: Assisted oocyte activation (AOA) can restore fertilization rates after IVF/ICSI cycles with fertilization failure. AOA is an experimental technique, and its downstream effects remain poorly characterized. Clarifying the relationship between AOA and embryo, morphokinetics could offer complementary insights into the quality and viability of the embryos obtained with this technique. The aim of this study is to compare the preimplantation morphokinetic development of embryos derived from ICSI-AOA (experimental group) vs. ICSI cycles (control group). METHODS: A retrospective cohort study was carried out with 141 embryos from fresh oocyte donation cycles performed between 2013 and 2017; 41 embryos were derived from 7 ICSI-AOA cycles and 100 embryos from 18 ICSI cycles. Morphokinetic development of all embryos was followed using a time-lapse system. RESULTS: We show that embryos from both groups develop similarly for most milestones, with the exception of the time of second polar body extrusion (tPB2) and the time to second cell division (t3). CONCLUSIONS: We conclude that ionomycin mediated AOA does not seem to affect the morphokinetic pattern of preimplantation embryo development, despite the alterations found in tPB2 and t3, which could directly reflect the use of a Ca2+ ionophore as a transient and quick non-physiologic increase of free intracytoplasmic Ca2+.

Efficiency and efficacy of vitrification in 35 654 sibling oocytes from donation cycles.

STUDY QUESTION: Is oocyte vitrification/warming as efficient and effective as using fresh oocytes in donation cycles? SUMMARY ANSWER: IVF with vitrified donor oocytes is less efficient than using fresh oocytes, but its efficacy remains comparable to that of fresh cycles. WHAT IS KNOWN ALREADY: Oocyte vitrification is used to preserve the reproductive potential of oocytes. A small number of randomized controlled trials carried out by experienced groups have shown that this technique provides fertilization, pregnancy, implantation and ongoing pregnancy rates comparable to those of fresh oocytes. However, large registry-based analyses have consistently reported lower live birth rates (LBRs) in cycles using vitrified oocytes. It is not clear whether this decrease may be due to the effect of vitrification per se on the oocytes or to the lower efficiency of the technique, as some of the oocytes do not survive after warming. STUDY DESIGN, SIZE, DURATION: Retrospective cohort analysis of 1844 cycles of oocyte donation (37 520 oocytes), each donor in the study provided enough oocytes for at least one reception cycle with fresh oocytes (2561 cycles) and one reception cycle with vitrified oocytes (2471 cycles) from the same ovarian stimulation (sibling oocytes). Overall, 35 654 oocytes were considered in the analysis. All embryo transfers (n = 5032) were carried out between 2011 and 2017. PARTICIPANTS/MATERIALS, SETTING, METHODS: Differences in reproductive outcomes after the first embryo transfer were evaluated using Pearson's Chi-squared test and regression analysis adjusted for recipient's age, BMI, sperm origin and state, day of embryo transfer, morphological score and number of transferred embryos. We performed two additional sub-analyses, to test whether the efficiency and/or effectiveness of vitrification/warming impacts reproductive results. One analysis included paired cycles where the same number of fresh and vitrified oocytes were available for ICSI (SAME sub-analysis), while the second analysis included those cycles with a 100% survival rate post-warming (SAME100 sub-analysis). MAIN RESULTS AND THE ROLE OF CHANCE: Baseline and cycle characteristics of participants were comparable between groups. Overall, fertilization rates and embryo morphological scores were significantly lower (P < 0.001) when using vitrified oocytes; moreover, vitrified oocytes also resulted in lower reproductive outcomes than sibling fresh oocytes using both unadjusted and adjusted analyses: ongoing pregnancy (32.1% versus 37.5%; P < 0.001; OR 0.88, 95% CI 0.77, 1.00) and live birth (32.1% versus 31.9%; P = 0.92; OR 1.16, 95% CI 0.90, 1.49). However, when the efficiency of warming was taken into account, reproductive outcomes in recipients became comparable: ongoing pregnancy (33.5% versus 34.1%; P = 0.82; OR 1.11, 95% CI 0.87, 1.43) and LBR (32.1% versus 32%; P = 0.97; OR 1.15, 95% CI 0.89, 1.48). Moreover, after selecting only cycles that, in addition to having the same number of oocytes available for ICSI, also had 100% post-warming survival rate in the vitrified group, reproductive outcomes were also comparable between fresh and vitrified oocytes: ongoing pregnancy (34.8% versus 32.4%; P = 0.42; OR 1.32, 95% CI 0.98, 1.77) and live birth (32.9% versus 31.0%; P = 0.52; OR 1.27, 95% CI 0.95, 1.71), indicating that reproductive outcomes of these cycles are affected by the efficiency of the vitrification/warming technique performed rather than the oocyte damage due to the fast cooling process to which oocytes are subjected. LIMITATIONS, REASONS FOR CAUTION: An open vitrification system was used for all cases, and oocyte vitrification/warming was performed by experienced embryologists with consistently high survival rates; caution must be exerted when extrapolating our results to data obtained using other open vitrification systems, closed vitrification systems or to IVF units with survival rates <90%. WIDER IMPLICATIONS OF THE FINDINGS: This is the largest cohort study comparing reproductive outcomes of vitrified and fresh sibling donor oocytes to date. We found that, when the number of oocytes available after warming is equal to the number of fresh oocytes, reproductive results including live birth are comparable. Consequently, the efficiency of vitrification must be taken into account to achieve the same reproductive outcomes as with fresh oocytes. We recommend implementing strict indicators of vitrification/warming efficiency in clinics and refining vitrification/warming protocols to maximize survival. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by intramural funding of Clínica EUGIN and by the Secretary for Universities and Research of the Ministry of Economy and Knowledge of the Government of Catalonia (GENCAT 2015 DI 048). The authors declare no conflicts of interest. TRIAL REGISTRATION NUMBER: N/A.

A freeze-all strategy does not increase live birth rates in women of advanced reproductive age.

RESEARCH QUESTION: Does a freeze-all strategy improve live birth rates in women of different age groups? DESIGN: Retrospective cohort study of 1882 first embryo transfer cycles, performed between January 2013 and December 2015. Reproductive outcomes between fresh (FRESH) or frozen (FROZEN) embryo transfers were compared in patients stratified by age: < 35, between 35 and 38, or > 38 years. Student's t test for independent samples and χ2 analyses were used as needed. A multivariable logistic regression analysis was performed adjusting for age, triggering drug, number of retrieved oocytes, number of transferred embryos, and percentage of top-quality embryos. MAIN RESULTS AND THE ROLE OF CHANCE: Live birth rates (LBR) were significantly higher for FROZEN in the < 35 years group (43.7% vs 24%; p < 0.001). In both the 35-38 and > 38 years groups, LBR for FROZEN vs FRESH were not statistically different (30.9% in the FROZEN group vs 29.3% in the FRESH group, p = 0.70, and 19.8% in the FROZEN group vs 12.7% in the FRESH group, p = 0.07, respectively). The multivariate analysis found a significantly positive effect of performing FROZEN on LBR in the younger group (OR 2.46, 95% CI 1.31-4.62; p = 0.005) but had no impact in women between 35 and 38 years (OR 1.01, 95% CI 0.55-1.83; p = 0.98) or older (OR 0.96, 95% CI 0.43-2.13; p = 0.92). CONCLUSIONS: Performing a freeze-all strategy seems to result in better reproductive outcomes when compared with a fresh ET in women under 35 years, with no significant impact on older women.

Medroxyprogesterone acetate versus ganirelix in oocyte donation: a randomized controlled trial.

STUDY QUESTION: Is oral medroxiprogesterone acetate (MPA) non-inferior compared to ganirelix with respect to the number of mature oocytes (MII) retrieved at ovum pick-up (OPU) in oocyte donation cycles? SUMMARY ANSWER: MPA is comparable to ganirelix in terms of number of MII retrieved at OPU in oocyte donation cycles. WHAT IS KNOWN ALREADY: Oral treatment with MPA inhibits the pituitary LH surge during ovarian stimulation in infertile patients. Because of its negative effect on the endometrium, MPA suppression is combined with freeze-all. Published reports indicate that both the number of MII retrieved and pregnancy rates from these oocytes are comparable to short protocol of GnRH agonists during IVF cycles with freeze-all. MPA might allow for more comfortable and cost-effective ovarian stimulation. STUDY DESIGN, SIZE, DURATION: Randomized clinical trial, open-label, single center, to assess the non-inferiority of MPA (10 mg/day) versus ganirelix (0.25 mg/day) from Day 7, in ovarian stimulation cycles triggered with triptoreline acetate. Trigger criterion was ≥3 follicles of diameter >18 mm. PARTICIPANTS/MATERIALS, SETTING, METHODS: Overall, 252 oocyte donors were selected (eligible), 216 were randomized and 173 reached OPU: 86 under MPA and 87 under ganirelix. The main outcome was the number of MII retrieved at OPU. Secondary outcomes were embryological laboratory outcomes and reproductive outcomes in recipients. The study was powered to test that the lower limit of the 95% confidence interval of the difference in retrieved MII between groups will be above the non-inferiority limit of -3. Differences were tested using a two-sided Student's t-test or a Pearson's Chi2 test, as appropriate. MAIN RESULTS AND THE ROLE OF CHANCE: All participants were in their first cycle of oocyte donation. On average, donors were 24 (SD 4.5) years old and with a BMI of 23 (SD 2.9) kg/m2. Duration of stimulation was similar in both groups (11.2 days), as well as the total gonadotropin dose up to trigger (2162 IU in MPA and 2163 IU in ganirelix). The number of MII retrieved was no different: 15.1 (SD 8.3) with MPA and 14.6 (SD 7.0), 95% CI of the difference -2.78, -1.83 excluding the pre-defined non-inferiority limit (-3). Recipients and embryo transfer (ET) characteristics were also similar between groups. The average age of recipients was 42 (SD 4.8) years and the BMI was 24 (SD 4.4) kg/m2. The mean number of MII assigned to each recipients was 6.7 (SD 1.2) in MPA and 6.6 (SD 1.2) in ganirelix (P = 0.58). MII were fertilized with partner sperm in 84% cycles overall and fertilization rate was 76% in MPA versus 74% in ganirelix (P = 0.34). Overall, there was 54% of double ET and 46% of single ET, with 40% of ETs were performed in D5. In spite of similar recipients and cycle characteristics, reproductive outcomes were unexpectedly lower with MPA. Biochemical pregnancy rate was 44 versus 57% (P = 0.023); clinical pregnancy rate 31 versus 46% (P = 0.006); ongoing pregnancy rate 27 versus 40%, (P = 0.015) and live birth rate 22 versus 31%, (P = 0.10). LIMITATIONS, REASONS FOR CAUTION: Although oocyte recipient and ET characteristics are similar among groups, this RCT has been designed under a hypothesis of non-inferiority in the number of MII obtained and recipients were not randomized; therefore, the reproductive outcomes in recipients should be evaluated with extreme caution. WIDER IMPLICATION OF THE FINDINGS: Ovarian stimulation using MPA for prevention of LH surge yields comparable number of MII oocytes compared to ganirelix in oocyte donation cycles. The unexpected finding in reproductive outcomes should be further investigated. STUDY FUNDING/COMPETING INTEREST(S): None to report. TRIAL REGISTRATION NUMBER: EudraCT number: 2015-004328-73; ClinicalTrials.gov Identifier: NCT02796105. TRIAL REGISTRATION DATE: 29 September 2015 (EudraCT); 9 June 2016 (ClinicalTrials.gov). DATE OF FIRST PATIENT'S ENROLLMENT: The date of enrollment of the first participant was 07 July 2016, and the last participant last visit in the study was on 10 July 2017.

Altered cytoplasmic maturation in rescued in vitro matured oocytes.

STUDY QUESTION: Do culture conditions affect cytoplasmic maturation in denuded immature non-GV oocytes? SUMMARY ANSWER: The maturation rate of denuded non-GV oocytes is not affected by culture media, but in vitro maturation seems to alter the mitochondrial membrane potential, endoplasmic reticulum (ER) and actin cytoskeleton compared with in vivo maturation. WHAT IS KNOWN ALREADY: In vitro maturation of denuded immature non-GV oocytes benefits cycles with poor in vivo MII oocyte collection, but maturation levels of non-GV oocytes are only scored by polar body extrusion. Since oocyte maturation involves nuclear as well as cytoplasmic maturation for full meiotic competence, further knowledge is needed about cytoplasmic maturation in in vitro culture. STUDY DESIGN, SIZE, DURATION: This basic research study was carried out between January 2017 and September 2018. PARTICIPANTS/MATERIALS, SETTING, METHODS: A total of 339 denuded immature non-GV oocytes were cultured in SAGE 1-Step (177) or G-2 PLUS (162) for 6-8 h after retrieval, and 72 in vivo matured MII oocytes were used as controls. Cultured immature non-GV oocytes were scored for polar body extrusion and analysed for mitochondrial membrane potential (ΔΨm), ER clusters, cortical granules number and distribution, spindle morphology and actin cytoskeleton organization. The obtained parameter values were compared to in vivo matured MII oocyte parameter values. MAIN RESULTS AND THE ROLE OF CHANCE: The maturation rates of oocytes cultured in G-2 PLUS and SAGE 1-Step were similar (65% vs 64.2%; P = 0.91). The differences observed in cortical granule density were not statistically significant. Also spindle morphometric parameters were mostly similar between in vitro and in vivo matured MII oocytes. However, the number of ER clusters, the ΔΨm and the cortical actin thickness showed significant differences between in vivo MII oocytes and denuded immature non-GV oocytes cultured in vitro until meiosis completion. LIMITATIONS, REASONS FOR CAUTION: Frozen-thawed oocytes together with fresh oocytes were used as controls. Due to technical limitations (fixation method and fluorochrome overlap), only one or two parameters could be studied per oocyte. Thus, a global view of the maturation status for each individual oocyte could not be obtained. WIDER IMPLICATIONS OF THE FINDINGS: Characterization of in vitro matured oocytes at the cellular level will help us to understand the differences observed in the clinical outcomes reported with rescue IVM compared to in vivo MII oocytes and to improve the culture methods applied. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by intramural funding of Clinica Eugin and by the Torres Quevedo Program to A.F.-V. from the Spanish Ministry of Economy and Competitiveness. No competing interests are declared.

Comparison of two different oocyte vitrification methods: a prospective, paired study on the same genetic background and stimulation protocol.

STUDY QUESTION: Can two different methods for oocyte vitrification, one using an open tool and the other a closed tool, result in similar oocyte survival rates? SUMMARY ANSWER: The oocyte survival rate was found to be higher in the closed method. WHAT IS KNOWN ALREADY: Open vitrification is performed routinely in oocyte donation cycles. Closed oocyte vitrification may result in slower cooling rates and thus it is less used, even though it has been recommended in order to avoid the risk of cross-contamination between material from different patients. STUDY DESIGN, SIZE, DURATION: This is a prospective cohort study with sibling oocytes carried out in a fertility center between July 2014 and January 2016. The study included 83 oocyte donors each providing a minimum of 12 mature oocytes (metaphase II: MII) at oocyte retrieval. Oocyte survival rate and fertilization rate, as well as reproductive outcomes (biochemical, clinical, ongoing pregnancy and live birth rates) per embryo transfer and also cumulatively between the two methods were compared by Chi2 tests. PARTICIPANTS/MATERIALS, SETTING, METHODS: Donor oocytes were denuded and six MII oocytes from each donor were vitrified using an open method and later assigned to one recipient, while another six MII oocytes were vitrified using a closed method and assigned to a different recipient (paired analysis). ICSI was used in all cases and embryo transfer was performed on Day 2-3 in all cases. MAIN RESULTS AND THE ROLE OF CHANCE: Oocyte donors were 24.8 years old on average (SD 4.7). Recipient age (average 41.2 years, SD 4.7) and BMI (mean 23.8 kg/m2, SD 4.0) were similar between recipient groups. Oocytes vitrified using the closed method had higher survival rate (94.5% versus 88.9%, P = 0.002), but lower fertilization rate (57.1% versus 69.8%, P < 0.001) compared to the open method. The number of fresh embryos transferred in the two groups was 1.8 on average (SD 0.4). Biochemical (45% closed versus 50% open), clinical (40% versus 50%) and ongoing (37.5% versus 42.5%) pregnancy rates were not different between groups (P > 0.05) and neither were live birth rates (37.5% versus 42.5%, P > 0.05). Cumulative reproductive results (obtained after the transfer of all the embryos) were also similar between groups. LIMITATIONS, REASONS FOR CAUTION: The participants of this study were oocyte donors, i.e. young women in good health, and care should be exerted in extending our results to other populations such as infertility patients, oncofertility patients and women freezing oocytes to delay childbearing. WIDER IMPLICATIONS OF THE FINDINGS: Our results suggest that, in spite of different survival and fertilization rates, closed and open oocyte vitrification methods should offer similar reproductive outcomes up to cumulative live birth rates. STUDY FUNDING/COMPETING INTEREST(S): The authors report no conflict of interest. Vitrolife provided the media and the closed method tool needed for the study at no cost.

A novel transnational fresh oocyte donation (TOD) program based on transport of frozen sperm and embryos.

STUDY QUESTION: What is the clinical efficacy of an oocyte donation program based on the transportation of frozen semen and embryos between two countries? SUMMARY ANSWER: The transnational oocyte donation program is efficient and reliable and it could provide a first-line strategy to overcome the lack of donors in some countries. WHAT IS KNOWN ALREADY: While there is increasing need for donated oocytes, in many countries the availability of donors is still insufficient to cover the therapeutic demands, and patients are referred abroad for treatment. Since embryo cryopreservation is reliable and efficient, we propose a strategy based on frozen embryos instead of frozen oocytes to satisfy the increasing demand for cross border oocyte donation. STUDY DESIGN, SIZE, DURATION: This is a retrospective cohort study including 630 patients treated from December 2015 to July 2017. PARTICIPANTS/MATERIALS, SETTING, METHODS: Infertile women were treated with elective vitrified-thawed embryo shipping and embryo transfer (ET) between two IVF clinics, one in Spain and one in Italy. MAIN RESULTS AND THE ROLE OF CHANCE: A total of 2617 embryos were created for the 630 patients and the survival rate after warming was 98.5%. After the first ET the live birth rate (LBR) was 30.6%. In 476 patients (75.5%), embryos were transferred at the cleavage stage (Day 2 or 3) and the LBR was 29.2%. Vitrified blastocysts were available for 154 patients (24.5%) and the LBR was 35%. Among patients who did not achieve a pregnancy after the first frozen ET (FET), 92.5% had at least one frozen embryo for successive procedures. 213 patients underwent a second FET. The LBR at the second FET was 30%. The cumulative LBR at the end of the observation period was 39.3%. LIMITATIONS, REASONS FOR CAUTION: The study design was retrospective. A direct comparison with vitrified oocyte donors cycle and subsequent fresh ET would have permitted to compare this strategy versus the current standard based on vitrified gametes. WIDER IMPLICATIONS OF THE FINDINGS: The LBR found in our study is more than acceptable and seems to be higher than what reported with vitrified oocytes. The transnational fresh oocyte donation program may have several advantages over the shipment of vitrified oocytes: similarly to the fresh oocyte donation program it allows for personalized care in oocyte recipient, which is provided by assigning a flexible number of oocytes, and at the same time it maintains the benefit of a frozen ART program permitting scheduling flexibility. The TOD program is efficient and may be proposed as a first-line strategy for distance and inter-countries oocyte donation programs. STUDY FUNDING, COMPETING INTEREST(S): None. TRIAL REGISTRATION NUMBER: NA.

A follow-up study of the long-term satisfaction, reproductive experiences, and self-reported health status of oocyte donors in Spain.

Purpose: The aim of this study is to evaluate the health of oocyte donors and explain how they regard their experience in the long-term. Materials and methods: This is a cross-sectional study in a single fertility centre that consists of a telephone interview guided by a semi-structured questionnaire covering several aspects of reproductive health and personal experience. Results: At the time of interview, 84 out of 121 women (69%) had children while 64 (53%) were already mothers at the time of their donation. Of the 38 women achieving a pregnancy after donation, five reported six pregnancy complications. Two out of 121 (2%) women reported being in menopause (aged 41 and 45). Twenty-three women (19%) reported gynaecological issues and eight (7%) reported fertility problems, although only four consulted a specialist. Most of women highlighted positive feelings about their donation (113, 93%) and 155 (97%) would recommend donating. Less than half (53, 44%) mentioned some negative aspects, mainly related to physical discomfort: injections (20,17%), pain (17, 14%), and side effects of ovarian stimulation (10, 8%). Conclusion: The impact of donation on women's life was mostly favourable, with the majority of participants reporting positive aspects and recommending donation, although some negative feelings as physical discomfort also arose. Therefore, more comfortable stimulation protocols could be developed.

Is there a relation between the time to ICSI and the reproductive outcomes?

STUDY QUESTION: Does time to ICSI affect reproductive outcomes? SUMMARY ANSWER: Biochemical and clinical pregnancy diminish progressively as time between oocyte pick up (OPU) and ICSI increases after fresh embryo transfer. WHAT IS KNOWN ALREADY: Appropriate oocyte cytoplasmic and nuclear maturation are of paramount importance to ensure an optimal embryonic developmental competence. While nuclear maturation is usually attained by the time an oocyte reaches OPU, cytoplasmic maturation cannot be readily assessed and might be incomplete. On the other hand, excessive in vitro culture of mature human oocytes can affect their ultrastructural characteristics and, in mice, induces alterations in gene expression and changes of chromatin and histone modification patterns. STUDY DESIGN, SIZE, DURATION: Retrospective consecutive cohort study including 1468 ICSI cycles carried out in a single center between December 2012 and September 2015. All cycles were with patient's own oocytes and fresh embryo transfer (ET). A radiofrequency-based system was used to record exact culture times, namely, OPU-denudation (DN); DN-ICSI and OPU-ICSI. We analyzed the effect of total and partial time intervals between procedures, from OPU to ICSI, on fertilization rate and biochemical, clinical, ongoing pregnancy and live birth rates. PARTICIPANTS/MATERIALS, SETTING, METHODS: Differences in laboratory times between positive and negative biochemical, clinical, ongoing pregnancies and birth results were tested by Mann-Whitney U test. The likelihood of positive clinical outcomes was further modeled by locally weighted scatterplot smoothing (LOWESS) regression and logistic regression, adjusting for woman's age and BMI, number of transferred embryos; mean embryo morphological score, sperm origin and status, and number of mature oocytes obtained at OPU. Effect of time on fertilization rate was modeled by Generalized Linear Modeling (GLM) and LOWESS regression. MAIN RESULTS AND THE ROLE OF CHANCE: The mean woman's age was 38.4 years (SD 4.6). Biochemical, clinical, ongoing pregnancy and live birth rates after the fresh ET were: 39.6, 33.1, 25.7 and 20.8%, respectively. Cumulative values for biochemical pregnancy and live birth were 46.4 and 26.3%, respectively. Mean times in hours for OPU-DN, DN-ICSI and OPU-ICSI were: 1.00 (SD 0.20); 3.86 (SD 1.93) and 4.87 (SD 1.96), respectively, and were not different for pregnant and non-pregnant patients. However, multivariate analyses showed that on average (anti-log transformed), each 1-h increase in the OPU-ICSI time reduced the likelihood of biochemical pregnancy by 7.3% (95% CI: 0.7-13.5%) and of clinical pregnancy by 7.7% (95% CI 0.8-14.1%), after the fresh ET. No effect of time was observed for ongoing pregnancy or live birth rates. Increasing OPU-ICSI time increased the fertilization rate (B = 0.052, 95% CI: 0.022, 0.082). LIMITATIONS, REASONS FOR CAUTION: The lack of relationship between incubation time of oocytes and live birth rates might be due to uncontrolled variables. Given the population analyzed, these results should not be extended to other ART protocols such as in vitro maturation of oocytes or classical IVF fertilization. WIDER IMPLICATIONS OF THE FINDINGS: This study indicates that in vitro ageing of mature oocytes significantly affects the chances to become pregnant. Effect on live birth rates, although not evident in this study, cannot be excluded. Limiting incubation time of mature oocytes in the embryology laboratory should improve reproductive results for patients using their own oocytes and with a transfer of fresh embryos. STUDY FUNDING/COMPETING INTEREST(S): None. TRIAL REGISTRATION NUMBER: NA.

The transcriptome of human oocytes is related to age and ovarian reserve.

STUDY QUESTION: How does the human oocyte transcriptome change with age and ovarian reserve? SUMMARY ANSWER: Specific sets of human oocyte messenger RNAs (mRNAs) and non-coding RNAs (ncRNAs) are affected independently by age and ovarian reserve. WHAT IS KNOWN ALREADY: Although it is well established that the ovarian reserve diminishes with increasing age, and that a woman's age is correlated with lower oocyte quality, the interplay of a diminished reserve and age on oocyte developmental competence is not clear. After maturation, oocytes are mostly transcriptionally quiescent, and developmental competence prior to embryonic genome activationrelies on maternal RNA and proteins. STUDY DESIGN, SIZE, DURATION: A total of 36 vitrified/warmed MII oocytes from 30 women undergoing oocyte donation were included in this study, processed and analyzed individually. PARTICIPANTS/MATERIALS, SETTING, METHODS: Total RNA from each oocyte was independently isolated, amplified, labeled, and hybridized on HTA 2.0 arrays (Affymetrix). Data were analyzed using TAC software, in four groups, each including nine oocytes, according to the woman's age and antral follicular count (AFC) (mean ± SD): Young with High AFC (YH; age 21 ± 1 years and 24 ± 3 follicles); Old with High AFC (OH; age 32 ± 2 years and 29 ± 7 follicles); Young with Low AFC (YL; age 24 ± 2 years and 8 ± 2 follicles); Old with Low AFC (OL; age 34 ± 1 years and 7 ± 1 follicles). qPCR was performed to validate arrays. MAIN RESULTS AND THE ROLE OF CHANCE: We identified a set of 30 differentially expressed mRNAs when comparing oocytes from women with different ages and AFC. In addition, 168 non-coding RNAs (ncRNAs) were differentially expressed in relation to age and/or AFC. Few mRNAs have been identified as differentially expressed transcripts, and among ncRNAs, a set of Piwi-interacting RNAs clusters (piRNAs-c) and precursor microRNAs (pre-miRNAs) were identified as increased in high AFC and old groups, respectively. Our results indicate that age and ovarian reserve are associated with specific ncRNA profiles, suggesting that oocyte quality might be mediated by ncRNA pathways. LARGE SCALE DATA: Data can be found via GEO accession number GSE87201. LIMITATIONS, REASONS FOR CAUTION: The oldest woman included in the study was 35 years old, thus our results cannot readily be extrapolated to women older than 35 or infertile women. WIDER IMPLICATIONS OF THE FINDINGS: We show, for the first time, that several non-coding RNAs, usually regulating DNA transcription, are differentially expressed in relation to age and/or ovarian reserve. Interestingly, the mRNA transcriptome of in vivo matured oocytes remains remarkably stable across ages and ovarian reserve, suggesting the possibility that changes in the non-coding transcriptome might regulate some post-transcriptional/translational mechanisms which might, in turn, affect oocyte developmental competence. STUDY FUNDING AND COMPETING INTEREST(S): This work was supported by intramural funding of Clinica EUGIN and by the Secretary for Universities and Research of the Ministry of Economy and Knowledge of the Government of Catalonia. J.H. and A.S. are employees of Affymetrix, otherwise there are no competing interests.

There is no evidence that the time from egg retrieval to embryo transfer affects live birth rates in a freeze-all strategy.

STUDY QUESTION: Does the time from ovum pick-up (OPU) to frozen embryo transfer (FET) affect reproductive outcomes in a freeze-all strategy? SUMMARY ANSWER: Our study did not detect statistically significant differences between first and subsequent cycles, clinically relevant differences are not ruled out and further and larger studies are required. WHAT IS KNOWN ALREADY: Following controlled ovarian hyperstimulation (COH) delaying FET until the endometrium has returned to an optimal pre-stimulation state may have a significant emotional impact on patients, which adds to the stress and anxiety accompanying a standard IVF cycle. Currently there is no agreement on the best time to perform a FET after a freeze-all cycle in order to maximize reproductive outcomes for the patient. STUDY DESIGN, SIZE, DURATION: Retrospective cohort study of 512 freeze-all cycles, performed between January 2012 and December 2014. COH was performed by either a GnRH antagonist (n = 397) or a long GnRH agonist protocol (n = 115). Ovulation was triggered using either a GnRH agonist (n = 258) or hCG (n = 254). Endometrial preparation was performed in an artificial cycle by either oral (n = 238) or transdermal (n = 274) oestrogen. Differences were considered significant if P < 0.05. PARTICIPANTS/MATERIALS, SETTING, METHODS: Reproductive outcomes between FETs which took place either within the first menstrual cycle following OPU (Cycle 1; n = 263) or afterwards (Cycle ≥2; n = 249) were compared. Student's t-test for independent samples, Mann-Whitney U-test and Chi-square analysis were used where appropriate. A multivariable logistic regression analysis was performed adjusting for maternal age, drug used for ovulation trigger, number of retrieved oocytes, number of embryos obtained, day of embryonic development at transfer, number of embryos transferred and type of endometrial preparation. Differences were considered significant if P < 0.05. MAIN RESULTS AND THE ROLE OF CHANCE: Live birth rate (LBR) was significantly higher in FET performed during Cycle 1 vs Cycle ≥2 (37.6% vs 27.3%, respectively; P = 0.01) before adjusting for confounding factors. We found no difference for biochemical pregnancy (49.8% vs 43.8%; P = 0.17), clinical pregnancy (44.1% vs 36.1%; P = 0.07) or pregnancy loss (11.8% vs 16.1%; P = 0.16). A multivariable analysis found no impact of timing of elective FET on LBR (odds ratio, OR 0.73; 95% CI 0.49-1.08). The impact remained not significant after adjusting for number of retrieved oocytes, drug used for ovulation trigger (hCG vs GnRH agonist) and reason for cryopreservation. The factors that significantly affected LBR were: maternal age in both age categories (women between 35 and 40 years vs women below 35 years, OR 0.63, 95% CI 0.4-0.95; and women over 40 years vs women below 35 years, OR 0.34, 95% CI 0.2-0.7), day of embryonic development at transfer (day +4 vs +3; OR 1.7, 95% CI 1.1-2.8) and number of transferred embryos (OR 2.2, 95% CI 1.4-3.3) and oestrogen used for endometrial preparation (transdermal vs oral; OR 0.62, 95% CI 0.4-0.9). LIMITATIONS REASONS FOR CAUTION: The main limitation of our study is its retrospective nature. Although we adjusted our statistical analysis for a number of known and suspected confounders, we cannot exclude the possibility of residual confounding factors. WIDER IMPLICATIONS OF THE FINDINGS: According to our results, clinicians might not need to wait more than one menstrual cycle before performing FET. This allows us to reduce unnecessary delays in FET, without compromising reproductive outcomes. STUDY FUNDING/COMPETING INTERESTS: No funding was sought for this study. Authors declare no competing interests. TRIAL REGISTRATION NUMBER: NA.

Quality of life, anxiety and depression of German, Italian and French couples undergoing cross-border oocyte donation in Spain.

STUDY QUESTION: What is the quality of life (QoL) and mental health of infertile heterosexual couples from different nations (Italy, Germany and France) undergoing cross-border oocyte donation (OD) in Spain? SUMMARY ANSWER: Women have lower QoL and more anxiety than their male partners; overall French couples have lower QoL than their Italian and German counterparts. WHAT IS KNOWN ALREADY: In Europe, thousands of couples move across national borders annually to seek ARTs, primarily OD, driven mainly by legal restrictions in their countries of origin. Most research shows that infertility and ARTs affect patients' mental health and QoL. The decision to undergo reproductive care abroad might add further emotional and practical complexity. Reliable information on how this experience affects the mental health and QoL of cross-border reproductive care (CBRC) patients is lacking. Moreover, most research has focused on women, and further research on male partners and intercultural differences is needed. STUDY DESIGN, SIZE, DURATION: Cross-sectional study including 548 heterosexual individuals (347 women, 201 men) from Italy, Germany and France seeking IVF with donated oocytes in Barcelona, Spain between March and November 2013. PARTICIPANTS/MATERIALS, SETTING, METHODS: A total of 432 couples were invited to participate and handed a questionnaire set. Questionnaires were answered separately and anonymously by each member of the couple on the day of embryo transfer. The questionnaire set included the Fertility Quality of Life (FertiQoL) instrument, the generic Hospital Anxiety and Depression Scale (HADS) instrument and three close-ended questions assessing perceived usefulness, desire, and use of psychological support. The overall response rate was 63.4%. MAIN RESULTS AND THE ROLE OF CHANCE: Men reported significantly higher scores than women in the emotional (+13.74; P < 0.001), mind-body (+13.39; P < 0.001) and social (+4.11; P < 0.01) FertiQoL domains, at multilevel analysis controlled for confounder factors. Intercultural differences in QoL of couples were seen. French individuals had significantly lower emotional (-6.44; P < 0.01), mind-body (-7.41; P < 0.001) and relational scores (-6.41; P < 0.001) compared to Italians. Germans showed higher social scores (+6.41; P < 0.001) but lower relational scores (-8.94; P < 0.002) than Italians. Men reported significantly lower anxiety scores for the HADS than their partners (-1.38; P < 0.001), and German couples reported lower anxiety (-1.70; P = 0.003) and depression than their Italian counterparts (-1.56; P < 0.001). French patients were more likely to have required support by a mental health professional due to fertility problems in the past (+0.19; P < 0.001). LIMITATIONS, REASONS FOR CAUTION: The scope of this study is limited to heterosexual couples undergoing cross-border OD. Caution on the interpretation of the results in men is advised, mainly because only three men for every five women completed the questionnaire. WIDER IMPLICATIONS OF THE FINDINGS: These findings call for further work to identify the true nature of the differences in QoL and mental health observed. STUDY FUNDING/COMPETING INTEREST(S): None.

Should we worry about the clock? Relationship between time to ICSI and reproductive outcomes in cycles with fresh and vitrified oocytes.

STUDY QUESTION: Is there an optimal time to perform ICSI with respect to the times of oocyte pick-up (OPU), in order to maximize the reproductive outcomes in cycles with fresh and vitrified/warmed donor oocytes? SUMMARY ANSWER: We found no significant differences in reproductive outcomes of ICSI cycles within a wide range of times between OPU and ICSI. WHAT IS KNOWN ALREADY: In assisted reproduction, the oocyte is subject to denudation, vitrification/warming and ICSI. As shorter interaction with cumulus cells, oocyte ageing in vitro and insufficient recovery after warming may all impact the resulting embryo developmental competence, strictly controlled times between procedures are often implemented. However, most protocols have not been tested with the aim to improve reproductive results, and little information is available on the ideal times to be followed during these steps in order to optimize fertilization rates and embryo quality, and to achieve the highest pregnancy rate. STUDY DESIGN, SIZE, DURATION: Data from 3986 ICSI cycles performed between December 2012 and May 2014 were included (3178 with fresh and 808 with vitrified/warmed donor oocytes). PARTICIPANTS/MATERIALS, SETTING, METHODS: ICSI was performed using donor oocytes and either partner or donor sperm. Exact times between OPU, denudation, vitrification, warming and ICSI were recorded automatically by a radiofrequency-based system. OPU was performed strictly 36 h after GnRH agonist trigger. Biochemical pregnancy was defined as a positive serum ßHCG 15 days after transfer, clinical pregnancy was defined as a visible embryo with heartbeat 5 weeks after transfer, and ongoing pregnancy was defined as a normally developing pregnancy at 12 weeks after transfer. MAIN RESULTS AND THE ROLE OF CHANCE: Times between OPU and ICSI (OPU-ICSI) ranged from 1 h 25 min to 17 h 13 min (averagefresh ± SD = 4 h 58 m ± 1 h; averagevitrified= 9 h 18 m ± 2 h). We found no effect of OPU-ICSI time on fertilization rate (pfresh=0.39; pvitrified=0.86) or embryo quality at Days 2 and 3 (pfresh=0.08; pvitrified=0.22). There was no difference in average OPU-ICSI times between positive and negative pregnancies (biochemical, clinical, ongoing and live birth rates) in either fresh (P = 0.71, 0.43, 0.79, 0.96) or vitrified (P = 0.59, 0.33, 0.73, 0.87) oocytes, respectively. Data were adjusted for oocyte donor age, semen status, number of motile spermatozoa and sperm concentration, and no effect of OPU-ICSI time on pregnancy and live birth rates for either fresh (P = 0.57, 0.16, 0.11, 0.46) or vitrified (P = 0.80, 0.73, 0.91, 0.95) oocytes was found. Further analysis for linear trend using OPU-ICSI time categorized in deciles showed that pregnancy rates and live birth rates do not increase or decrease across deciles. We found no effect of time taken for denudation to vitrification, warming to ICSI and denudation to ICSI on pregnancy rates. LIMITATIONS, REASONS FOR CAUTION: This is a study with automatically collected times from a high number of ICSI cases; however, its retrospective nature cannot exclude the influence of unaccounted for variables on the results. All oocytes came from oocyte donors (≤35 years old), so results cannot be extended to older or infertile women. WIDER IMPLICATIONS OF THE FINDINGS: Our results indicate that the effective window of time for insemination by ICSI might be wider than previously thought. It therefore appears that, within appropriate time frames, the management of ICSI cycles involving oocytes from young women in embryology laboratories could be adjusted to accommodate caseloads and workflow with no loss of oocyte viability or cycle efficiency.

Endometrial preparation: effect of estrogen dose and administration route on reproductive outcomes in oocyte donation cycles with fresh embryo transfer.

STUDY QUESTION: Is there a difference in live birth rates following endometrial preparation with either a constant or increasing estrogen dose in fresh embryo transfer from oocyte donation cycles? SUMMARY ANSWER: There is no difference in live birth rates between a constant dose versus an increasing dose of estrogen after fresh embryo transfer in oocyte donation cycles with oral or transdermal supplementation. WHAT IS KNOWN ALREADY: Endometrial preparation (EP) with estrogen and progesterone, and embryo-endometrial synchronicity are determinant for adequate embryo implantation. Estrogen is crucial and different exogenous administration patterns could imply variations on EP. Moreover, estrogen undergoes metabolization by the intestines and liver when administered orally, an effect that is bypassed by transdermal administration. Information on the effect of replacement patterns and route of administration of E on reproductive outcomes of women undergoing fresh embryo transfer from oocyte donation cycles is scarce. STUDY DESIGN, SIZE, DURATION: Retrospective cohort study including 8362 embryo transfers following ICSI, corresponding to 8254 patients, between October 2010 and March 2015. A total of 5593 (66.9%) patients received an increasing E dose (ID) (oral: 2 mg/day day(d)1-7, 4 mg days d8-12, 6 mg d13-embryo transfer; transdermal: 75 µg/3 days on d1-6, 150 µg/3 days d7-embryo transfer) while 2769 (33.1%) received a constant dose (CD) of estrogen (oral: 6 mg/day 1-embryo transfer; transdermal: 150 µg/3 days d1-embryo transfer). Embryos were generated by ICSI with fresh or vitrified donor oocytes fertilized with either fresh or frozen sperm from either the couple partner or donor. PARTICIPANTS/MATERIALS, SETTING, METHODS: Cohort allocation was not related to patient characteristics; instead it reflected an internal policy change in E administration. Effect of estrogen dose (ID versus CD) on biochemical, clinical, ongoing and live birth rates, stratified by administration route, was analyzed by univariate and multivariate analysis adjusted by donor and recipient demographic and cycle characteristics. MAIN RESULTS AND THE ROLE OF CHANCE: No difference in live birth rate was found between CD and ID for oral (33.0 versus 32.5%, P = 0.81) and transdermal (35.3 versus 33.5%, P = 0.33) supplementation. Biochemical pregnancy rate was higher in CD than ID (53.7 versus 47.5%, P < 0.001) when patients received oral supplementation. Adjusted analysis confirmed that oral administration had a greater impact on biochemical pregnancy rates than transdermal (odds ratio (OR) 1.28; 95% confidence interval (CI) 1.11-1.48, P = 0.001 versus OR 1.13; 95% CI 1.00-1.30, P = 0.055). Sub-analysis of transfers between day 12 and 15 of estrogen supplementation showed no difference between CD and ID in pregnancy outcomes. Demographic variables and cycle characteristics were comparable between both groups. Moreover, the use of the oocyte donation model reduces confounding factors related to oocyte age, embryo aneuploidy, and embryo quality. LIMITATIONS, REASONS FOR CAUTION: The greatest limitation of this study is its retrospective nature. On the other hand, this study was performed using donated oocytes; although this is unlikely to affect the results, we cannot exclude the possibility that a high quality female gamete responds differently to endometrial state in comparison to a patient's own oocytes. WIDER IMPLICATIONS OF THE FINDINGS: In fresh embryo transfer from oocyte donation cycles, changes in the protocol of E replacement do not seem to have an impact on clinical outcomes and performance; for this reason estrogen replacement protocols can be adjusted to the patient's characteristics and preferences as well as to the most cost effective strategy. STUDY FUNDING/COMPETING INTERESTS: None.

Use of donor sperm in addition to oocyte donation after repeated implantation failure in normozoospermic patients does not improve live birth rates.

STUDY QUESTION: Does switching to donor semen after at least three failed oocyte donation (OD) cycles with the partner normozoospermic semen increase the live birth rate in a subsequent OD cycle? SUMMARY ANSWER: Switching to donor semen after at least three failed OD cycles with the partner normozoospermic semen does not increase the live birth rate. WHAT IS ALREADY KNOWN: In some patients, a viable pregnancy cannot be achieved after several OD cycles, despite normal diagnostic findings for the couple. The ESHRE Capri Workshop Group indicates that, in order to improve reproductive outcomes, a semen donation can be offered after three failed ICSI cycles. STUDY DESIGN, SIZE, DURATION: A retrospective cohort analysis of fourth and fifth OD cycles with either the partner's normozoospermic semen (OD) or double-donation cycles (DD), performed between January 2011 and December 2014 in a private fertility center. These couples did not have a known male factor. PARTICIPANTS/MATERIALS, SETTING, METHOD: The study included 228 cycles (159 OD and 69 DD). The fertilization method was ICSI in all cycles and embryos were transferred fresh. Fertilization rates were compared between groups using ANOVA while pregnancy outcomes were compared using Chi-square tests. Effect of DD on pregnancy outcomes was further analyzed using a logistic regression model adjusted for recipient's age and BMI, number of embryos transferred, day of embryo transfer and morphological embryo quality score. MAIN RESULTS AND THE ROLE OF CHANCE: There was no difference in live birth rate between the DD and OD groups (38.2 versus 35.8%, P = 0.73), even after adjustment for confounding factors (odds ratio 1.41, 95% confidence interval 0.72, 2.76; P = 0.31). Rates of biochemical pregnancy (52.2 versus 54.1%, P = 0.79), clinical pregnancy (41.2 versus 45.9%, P = 0.51) and ongoing pregnancy (38.2 versus 37.1%, P = 0.87) were not different between the DD and the OD groups, as well as fertilization rate (75.3 versus 75.2%, P = 0.97). The DD and OD groups were comparable at baseline in all demographic and cycle variables analyzed (recipient's BMI, number of transferred embryos and embryo quality) with the exception of recipient's age (42.3 in DD versus 44.1 in OD, P = 0.005), and day of embryo transfer (56.5% of DD and 83.6% of OD embryo transfers were performed on blastocyst stage, P < 0.001); both variables were adjusted for in the multivariate analysis. LIMITATIONS, REASONS FOR CAUTION: The main limitations of this study are its retrospective nature, the relatively small sample size, the transfer of embryos of different developmental stages and the lack of extensive molecular testing, such as sperm DNA fragmentation test, in normozoospermic patients. WIDER IMPLICATIONS OF THE FINDINGS: After excluding several causes for the failed OD cycles, the partner's normozoospermic semen was a common factor in all of them. Nevertheless, the change to a donor's semen does not seem to improve the reproductive outcomes in the subsequent cycle. STUDY FUNDING/COMPETING INTERESTS: No extra-mural funding was obtained for this study. There are no conflicts of interest to declare. TRIAL REGISTRATION NUMBER: NA.