Pro: Fresh versus frozen embryo transfer. Is frozen embryo transfer the future?

Embryo cryopreservation has been an integral part of ART for close to 40 years and vitrification has boosted overall ART efficacy and safety. Recently, there has been a vivid scientific discussion on whether elective cryopreservation of all embryos (freeze-All) should be pursued for most patients, with a fresh embryo transfer taking place only in selected cases. In terms of efficacy, the available evidence suggests that the freeze-All strategy leads to higher live birth rates after the first embryo transfer compared to the conventional strategy in high responders, while there is no difference in normal responders. There is no evidence to suggest that the freeze-All strategy is inferior to the conventional strategy of fresh transfer when comparing cumulative live birth rates using data from all available randomized controlled trials. The incidence of ovarian hyperstimulation syndrome is significantly reduced in the freeze-All policy. However, regarding obstetric complications and neonatal outcomes, the evidence suggests that each strategy is associated with certain risks and, therefore, there is no approach that could be unequivocally accepted as safer. Similarly, limited evidence does not support the notion that patients would be universally against freeze-All owing to the inevitable delay in pregnancy achievement. Finally, the cost-effectiveness of freeze-All is likely to vary in different settings and there have been studies supporting that this policy can be, under certain conditions, cost-effective. Adoption of the freeze-All policy can also allow for more flexible treatment strategies that have the potential to increase efficacy, reduce cost and make treatment easier for patients and clinics. Importantly, freeze-All does not require the use of any experimental technologies, further training of personnel or the costly acquisition of new equipment. For these reasons, transitioning to the freeze-All policy for most patients appears to be the next logical step in ART

Evidence-based management of poor ovarian response.

Poor ovarian response is not infrequent and represents one of the major therapeutic challenges in in vitro fertilization. Although several tests have been proposed, which aim at predicting poor response to ovarian stimulation, available data are conflicting regarding their accuracy and clinical usefulness. Even though several therapeutic approaches have been explored, a single effective strategy has not yet been established. One of the major limitations of interpreting the relevant literature is the wide variability in the definitions used for poor ovarian response. Regarding the interventions that have been proposed to improve the probability of pregnancy in poor responders, limited evidence from relevant randomized controlled trials suggests that addition of growth hormone during ovarian stimulation, as well as performing embryo transfer on day 2 instead of day 3, might be beneficial. Further randomized control trials are warranted to reliably determine which would be the best approach for treating poor ovarian response.info:eu-repo/semantics/publishe

Parity: A key measure of confounding in data-linkage studies of outcomes after medically assisted reproduction

Parity is a potential confounder of the association between medically assisted reproduction (MAR) and health outcomes. This concept paper describes a population-based record linkage study design for selecting MAR-unexposed women matched to the parity of MAR-exposed women, at the time of the first exposure to MAR. Women exposed to MAR were identified from claims for government subsidies for relevant procedures and prescription medicines, linked to perinatal records. Women unexposed to MAR were identified from linked perinatal and death records, matched to exposed women by age, rurality, age of first child (if any) and parity at the date of first MAR. The availability of a longitudinal, whole-of-population dataset (“population spine”) based on enrolments in Australia's universal health insurance scheme was a critical design element. The example application examines cancer risk in women after exposure to MAR. Parity is a confounder in this setting because it is associated with MAR and hormone-sensitive cancers

Female age is associated with the optimal number of oocytes to maximize fresh live birth rates: an analysis of 256,643 fresh ART cycles

Research question: What is the optimal number of oocytes retrieved at which maximum live birth rate is observed after fresh autologous assisted reproductive technology (ART) cycles for women of different ages? Design: Retrospective cohort study of all fresh autologous ART aspiration cycles (n = 256,643) undertaken in Australia and New Zealand between 2009 and 2015. Primary outcome measure was live birth rate (LBR) (delivery of at least one liveborn baby at 20 weeks’ gestation or over per fresh aspiration cycle). Cycles were grouped according to female age (<30, 30–34, 35–49, 40–44 and ≥45 years) and ovarian response (one to three, four to nine, 10–14, 15–19, 20–25 and ≥25 oocytes). Secondary outcome was incidence of ovarian hyperstimulation syndrome (OHSS) requiring hospitalization. Results: At different oocyte yields, LBR per fresh aspiration cycle peaked and then declined at, depending on female age: <30 years: six to 11 oocytes (LBR 31–34%); 30–34 years: 11–16 oocytes (LBR 29–30%); 35–39 years: nine to 17 oocytes (LBR 21–24%); and 40–44 years: 15–17 oocytes (LBR 11–12%). The incidence of OHSS increased significantly with the number of oocytes retrieved, from 1.2% with 15 oocytes retrieved to 9.3% with 30 or more oocytes retrieved (P < 0.001). Conclusion: The optimal number of oocytes at which maximum LBR was observed in a fresh aspiration cycle was highly dependent on age. Because of the observational nature of the results, a cause–effect relationship between the number of oocytes retrieved and LBR should not be assumed; evidence from well-designed randomized control trials is required before clinical advice can be suggested