Biological and Biochemical factors Predictive of Oocyte survival, Fertilization, Pregnancy in oocyte thawing cycles

Optimization and monitoring of IVF treatments requires good data on the effect and magnitude of clinical factors affecting treatment outcome. Many factors have been known to affect IVF outcomes. Currently there are still no data to predict whether a patient who undergoes In Vitro Fertilization (IVF) cycles can be considered a good candidate for oocyte freezing. The aim of this study was therefore to evaluate which biological and biochemical factors can be predictive of oocyte survival and fertilization, as well as of clinical pregnancy in oocyte thawing cycles. This study showed that none of the factors available on the day of the pick-up is able to predict (in case of oocyte cryopreservation) the success of a subsequent oocyte thawing cycle. Only the transfer of at least one Grade 1 embryo after oocyte thawing cycle has a statistically significant impact on pregnancy. Unfortunately, this cannot be considered an elective factor to guide the clinician and/or the embryologist in choosing patient's treatment as it is not available on the day of the oocyte pick up but it is a result of oocyte thawing. Keywords: Oocyte thawing; Biological and biochemical markers; Fertilization rate; Ongoing pregnancy rate

P–770 Two in One - Monozygotic splitting and associated perinatal outcomes after oocyte freezing; an exploratory analysis of the UK national database from 1990 to 2016

Study question Is oocyte freezing a risk factor for monozygotic splitting? Summary answer There is a trend towards a higher monozygotic splitting incidence among frozen oocytes, but this did not reach statistical significance. What is known already Laboratory techniques which involve embryo manipulation such as ICSI, assisted hatching, embryo biopsy for pre-implantation genetic testing and extended culture to the blastocyst stage appear to increase the risk of monozygotic splitting. Whilst there is some data that embryo freezing does not appear to increase the risk of monozygotic splitting, there is no comparable analysis on whether oocyte freezing increases the risk of monozygotic splitting. Study design, size, duration This was a retrospective cohort study analysing 988 015 ART (assisted reproductive technique) cycles from the HFEA anonymised database from 1990 to 2016. As frozen oocytes require ICSI, only fresh oocytes with ICSI were taken for comparison and frozen embryo transfers were excluded. Only single embryo transfers were included.[CM1] [MM2] We also noted ages of the female partner at the time of treatment, stage of embryo transfer, and whether pre-implantation genetic testing had been performed. Participants/materials, setting, methods There were 84 085 ICSI cycles with single embryo transfers using fresh oocytes and 596 using frozen oocytes. Monozygotic splitting was defined as the presence of two foetal hearts [CM1] [MM2] on ultrasound. Live birth (LB)was defined as either a singleton or a twin LB resulting from a monozygotically split embryo. Preterm birth (PTB) was defined as birth prior to 37 weeks gestation and early PTB as birth prior to 32 weeks gestation. Main results and the role of chance The frozen oocyte group had fewer women in the under–35 age group (frozen oocytes 16.6% vs fresh oocytes 53.6%, p < 0.0001) and a higher proportion of blastocyst transfers ( frozen oocytes 55.1% vs fresh oocytes 48.8%, p = 0.002) There were only 10 PGT cycles amongst monozygotically split embryos from fresh oocytes in our analysis, and none in the frozen oocyte group. Hence, this was not included as a confounder. There was a non-significant trend toward a higher incidence of monozygotic splitting amongst frozen oocytes (4/596, 2.3%, all monozygotic twins) than amongst fresh oocytes (378/27 019, 1.4%, 372 monozygotic twins and 6 monozygotic triplets); OR 1.688, 95% CI 0.623 to 4.574 and aOR 1.506, 95% CI 0.531 to 4.274 (maternal age and stage of embryo transfer adjusted as confounders). Of the 378 monozygotically split embryos from fresh oocytes, 308 (81.5%) had a LB: of which 47 (15.3%) were singletons and the rest were twins; 241 (78.2%) were PTB and 56 (18.2%) were early PTB. Of the four monozygotic twins from frozen oocytes, all reached a LB; one was a singleton term LB (Birthweight 3–3.5kg) whilst three were twin preterm LBs at 35–36 weeks, with no early PTBs and twin median birthweight 2–2.5 kg. Limitations, reasons for caution Albeit a large national database, this cohort study was restricted due to absence of data on potential confounders such as age at oocyte freezing, method of cryopreservation and length of storage.[CM1] Data was also lacking on amnionicity, obstetric risks including pre-eclampsia, twin-to-twin-transfusion syndrome, intrapartum and late effects. Wider implications of the findings: With rapid rise in egg freezing, our findings would help reassure women that eggs on ice does not predispose to significant risk of two-in-one monozygotic splitting. However, the marginal trend (from 1.4% in fresh to 2.3% in frozen oocytes), does indicate that this subject merits further research. Trial registration number Not applicable. A database based retrospective study

Is Freezing the Future? Investigating Interest of Elective Oocyte Freezing Amongst Singaporean Women

A novel technological innovation called Elective Oocyte Freezing (EOF) has emerged as a solution for women who wish to preserve their fertility to delay childbearing for non-medical reasons. This technology has grown in popularity as women have undertaken a greater role in the workforce and faced the dilemma of balancing work and family. In spite of the rising trend of Singaporean women postponing childbearing to advance their careers, EOF is currently prohibited in Singapore. Many Singaporean individuals have declared this policy to be both outdated and a threat to women’s reproductive rights. However, prior to this survey, no research, to my knowledge, has analyzed Singaporean female professionals' interests in EOF, if made available. Through this quantitative, cross-sectional, 4-part survey, I conclude that if EOF was permitted, encouraged, and subsidised by the Singaporean government, Singaporean women possess a strong interest in freezing their eggs for social purposes This paper further demonstrates an existing positive relationship between 48 Singaporean female professionals’ interest in EOF prior to and following reading an information leaflet. Specifically, after being informed of the social benefits presented by EOF, participants were significantly more inclined to freeze their eggs if such practice was permitted in Singapore. This conclusion suggests that the Singaporean government should re-evaluate their position on EOF in order to facilitate childbearing dilemmas faced by the increasing number of women entering the country’s workforce each year. Additionally, as this policy is currently a subject of debate in Singapore, the implications of this research, revealing Singaporean female professionals’ interest in EOF, create a foundation for both future research and the possible evaluation of this policy. If this conclusion is corroborated with subsequent research, further evidence may substantiate my findings regarding the desires of Singaporean women and possibly result in a change of legislation.

Beyond Life and Death. Investigating Cryopreservation Practices in Contemporary Societies

Cryopreservation practices are an essential dimension of contemporary life sciences. They make possible the freezing and storage of cells, tissues and other organic materials at very low temperatures and the subsequent thawing of these at a future date without apparent loss of vitality. The article presents some initial ideas and central theses of a research project recently funded by the European Research Council (ERC). The CRYOSOCIETIES project is based on the thesis that in contemporary societies, cryopreservation practices bring into existence a new form of life: “suspended life”. “Suspended life” enables vital processes to be kept in a liminal state in which biological substances are neither fully alive nor dead. CRYOSOCIETIES examines the creation of “suspended life” through three ethnographic studies that investigate various sites of cryopreservation. The first deals with cord blood banking with the promise to store vitality and ensure health; the second addresses oocyte freezing to extend fertility and rearrange reproductive futures, while the third case study focusses on the emergence of “frozen zoos”, that is to say cryobanks which seek to preserve organic material of endangered or extinct animal species. The conclusion will rehearse the central aspects of the proposed project and point to further directions of research.

Oocyte Vitrification: A Comparative Analysis Between Fresh and Cryopreserved Oocytes in an Oocyte Donation Program

Background: Oocyte Cryopreservation has become an important part of infertility treatment for various reasons such as fertility preservation in women going for oncological treatment; in oocyte donation cycles; in eliminating several religious, ethical, and legal concerns of embryo freezing and in women who wish to delay childbirth. The newer ”vitrification” technique for freezing has further improved the success rates for actual conception than the earlier method of slow freezing. A successful oocyte freezing program can help in establishment of oocyte banks, which would help to provide compatible oocytes immediately, thus would eliminate the several problems of fresh donor cycles. Methods: In this retrospective observational study, total 60 oocyte donation cycles were included (38 were fresh and 22 were vitrified oocytes cycle, respectively). After a thorough screening, controlled ovarian hyperstimulation for donors was performed using flexible antagonist protocol. All mature oocytes were allocated into “vitrified oocytes” and “fresh oocytes” groups. Vitrification technique using Cryotop method was used for oocyte freezing. Both clinical and laboratory outcomes of vitrified and fresh oocytes in donor cycles were compared. Results: A total of 600 oocytes (226 “vitrified oocytes” and 374 fresh oocytes), were studied. After warming 218 oocytes survived resulting in survival rate of 96.4%. Fertilization rate and embryo formation rate was 86.2% and 93.6%, respectively. Results of frozen-thawed oocyte donor cycles were compared with fresh donation cycles. For fresh oocyte group, fertilization rate and embryo formation rate was 83.4% and 92.6%, respectively. On comparing clinical outcomes, clinical pregnancy rate was 60.5% in fresh group and 63.6% in vitrified group. Conclusions: Both clinical and laboratory results obtained in the study suggest that oocyte cryopreservation can be performed with reproducible success, thus vitrification technique can be provided as a useful tool for achieving highly successful outcomes in an oocyte donor program.