M. De Vos

Live birth rates following natural cycle IVF in women with poor ovarian response according to the Bologna criteria

STUDY QUESTION What is the effect of natural cycle IVF in women with poor ovarian response according to the new ESHRE definition for poor ovarian responders: the Bologna criteria? SUMMARY ANSWER Although natural cycle IVF is a promising treatment option for normal responders, poor ovarian responders, as described by the Bologna criteria, have a very poor prognosis and do not appear to experience substantial benefits with natural cycle IVF. WHAT IS KNOWN ALREADY Previous trials have shown that natural cycle IVF is an effective treatment for the general infertile population and might be an option for poor ovarian responders. However, none of the trials have examined the effect of natural cycle IVF in poor responders according to the Bologna criteria, the newly introduced definition by the ESHRE Working Group on Poor Ovarian Response Definition. In this trial, we examined the effect of natural cycle IVF in poor ovarian responders fulfilling the Bologna criteria. STUDY DESIGN, SIZE, DURATION In this retrospective cohort trial, 164 consecutive patients, undergoing 469 natural cycle IVFs between 2008 and 2011 were included. Patients were stratified as poor and normal responders: 136 (390 cycles) were poor ovarian responders according to the Bologna criteria, whereas 28 women (79 treatment cycles) did not fulfil the criteria and were considered as normal responders. PARTICIPANTS/MATERIALS, SETTING, METHODS All patients were monitored with hormonal analysis and ultrasound scan every second day, from Day 7 or 8 of the cycle onwards. When a follicle of >16 mm was observed, ovulation was triggered with 5000 IU of i.m. hCG and oocyte retrieval was performed 32 h later. MAIN RESULTS AND THE ROLE OF CHANCE Live birth rates in poor responders according to the Bologna criteria were significantly lower compared with the control group of women; the live birth rate per cycle was 2.6 versus 8.9%, P = 0.006 and the live birth rate per treated patient was 7.4 versus 25%, P = 0.005. In poor responders according to the Bologna criteria, live birth rates were consistently low and did not differ among different age groups (≤ 35 years, 36-39 years and ≥ 40 years), with a range from 6.8 to 7.9%. LIMITATIONS, REASONS FOR CAUTION A limitation of our analysis is its retrospective design; however, taking into account that we included only consecutive patients treated with exactly the same protocol, the likelihood of selection bias might be considerably limited. In addition, the control group in our study refers to women of younger age and therefore the promising results among patients who did not fulfil the Bologna criteria apply only to women of younger age. WIDER IMPLICATIONS OF THE FINDINGS Our trial suggests that although natural cycle IVF is a promising treatment option for younger normal responders, its potential is very limited to poor ovarian responders as described by the Bologna criteria, irrespective of patients age. This highlights the very poor prognosis of these women and therefore the urgent need for future trials to examine the effect of ovarian stimulation protocols in women with poor ovarian response as described by the Bologna criteria. STUDY FUNDING/COMPETING INTEREST(S) No funding was used. There are no competing interests to declare.

Reproductive potential of a metaphase II oocyte retrieved after ovarian stimulation: an analysis of 23 354 ICSI cycles

BACKGROUND Live birth per cycle and live birth per embryo transfer are commonly used outcome measures for IVF treatment. In contrast, the assessment of the reproductive efficiency of human oocytes fertilized in vitro is seldom performed on an egg-to-egg basis. This approach may however gain importance owing to the increasingly widespread use of oocyte cryopreservation, as the technique is becoming more established. The aim of the current study is to quantify the reproductive efficiency of the oocyte according to ovarian ageing and ovarian response. METHODS We performed a retrospective analysis of the outcome of all consecutive patients attending for treatment between 1992 and 2009. The outcome in terms of live birth after fresh and cryopreserved embryo transfer per mature oocyte was calculated for 207 267 oocytes retrieved in 23 354 ovarian stimulation cycles. The oocyte utilization rate (number of live births per mature oocyte) was further analysed in relation to the ovarian response. RESULTS The oocyte utilization rate in women in the age of ≤ 37 years remains constant with a mean of 4.47% live birth per mature oocyte [95% confidence interval (CI): 4.32-4.61]. From the age of 38 years onwards, a significantly lower oocyte utilization rate was noted, declining from 3.80% at the age of 38 years to 0.78% at 43 years (P < 0.001). In this 38-43 years age group, oocyte utilization rate was no longer dependent on ovarian response (P = 0.87). CONCLUSIONS The major strength of the study, which is also its weakness, is the fact that we included a large number of cycles performed over a long period of time. According to our results, the oocyte utilization rate between 23 and 37 years of age depends largely on ovarian response and to a much lesser extent on age. From the age of 38 years onwards, the utilization rate depends largely on age and to a much lesser extent on ovarian response. Considering the increased use of oocyte freezing for fertility preservation, these data are extremely valuable as they provide an estimate of the number of oocytes needed to achieve a live birth.

Can 200 IU of hCG replace recombinant FSH in the late follicular phase in a GnRH-antagonist cycle? A pilot study

BACKGROUND GnRH-antagonist protocols shorten the treatment period and reduce inconvenience for IVF patients. This randomised controlled trial (RCT) further explored whether low-dose hCG can be used clinically to replace recombinant FSH (rFSH) during the late follicular phase in a GnRH-antagonist protocol. METHODS Seventy ICSI patients undergoing controlled ovarian stimulation (COS) in a GnRH-antagonist protocol was randomized into two groups. The control group received a standard treatment with rFSH (Puregon) plus a GnRH-antagonist, daily from Day 6 of stimulation. In the study group, rFSH was discontinued when six follicles >or=12 mm were observed and estradiol levels were >600 ng/l; rFSH was subsequently replaced by low-dose hCG (200 IU/l daily). RESULTS Mean values (SD) for dose and duration of rFSH treatment in the control versus low-dose hCG group were 1617 (280) versus 1273 (260) IU rFSH [between-group difference -344, 95% confidence interval (CI) -483 to -205; P < 0.001], and 8.2 (1.6) versus 6.4 (1.3) days (-1.8, -2.6 to -1.1; P < 0.001), respectively. The mean number of metaphase II oocytes of 10.1 versus 8.9 (between-group difference -1.2, 95% CI -3.9 to 1.5) and the ongoing pregnancy rates of 10/35 (29%) versus 13/35 (37%) (between-group difference 8.6%; 95% CI -13.0 to 29.1%; P = 0.45) for control versus hCG, respectively, did not differ. CONCLUSION In this pilot trial, substitution of rFSH by low-dose hCG in the final days of COS leads to a reduction of FSH consumption whereas ICSI outcome, in terms of oocyte yield and ongoing pregnancy rate, remains comparable to the traditional regimen (ClinicalTrials.gov, trial number: NCT00750100).

Human in vitro oocyte maturation is not associated with increased imprinting error rates at LIT1, SNRPN, PEG3 and GTL2

STUDY QUESTION Does in vitro maturation (IVM) of cumulus-enclosed germinal vesicle (GV) stage oocytes retrieved from small antral follicles in minimally stimulated cycles without an ovulatory hCG dose induce imprinting errors at LIT1, SNRPN, PEG3 and GTL2 in human oocytes? SUMMARY ANSWER There is no significant increase in imprinting mutations at LIT1, SNRPN, PEG3 and GTL2 after IVM of cumulus-enclosed GV oocytes from small antral follicles in minimally stimulated cycles without hCG priming. WHAT IS KNOWN ALREADY Animal models have generally demonstrated correct methylation imprint establishment for in vitro grown and matured oocytes. For human IVM, well-designed studies allowing conclusions on imprint establishment are currently not available. STUDY DESIGN, SIZE, DURATION Immature oocyte-cumulus complexes from 2 to 9 mm follicles were retrieved in polycystic ovary syndrome (PCOS) subjects in minimally stimulated cycles without hCG priming and matured in vitro. In vivo grown oocytes were retrieved after conventional ovarian stimulation for IVF/ICSI or after ovulation induction. Imprinting error rates at three maternally methylated (LIT1, SNRPN and PEG3) and one paternally methylated (GTL2) imprinted genes were compared in 71 in vitro and 38 in vivo matured oocytes. PARTICIPANTS/MATERIALS, SETTING, METHODS The limiting dilution bisulfite sequencing technique was applied, allowing increased sensitivity based on multiplex PCR for the imprinted genes and the inclusion of non-imprinted marker genes for cumulus cell DNA contamination. MAIN RESULTS AND THE ROLE OF CHANCE In vitro as well as in vivo matured oocytes showed only a few abnormal alleles, consistent with epimutations. The abnormalities were more frequent in immature than in mature oocytes for both groups, although no significant difference was reached. There was no statistically significant increase in imprinting errors in IVM oocytes. LIMITATIONS, REASONS FOR CAUTION This single cell methylation analysis was restricted to a number of well-selected imprinted genes. Genome-wide methylation analysis of single human oocytes is currently not possible. WIDER IMPLICATIONS OF THE FINDINGS IVM is a patient-friendly alternative to conventional ovarian stimulation in PCOS patients and is associated with reduced gonadotrophin costs and avoidance of OHSS. The results of this study show for the first time that optimized human IVM procedures have no significant effects on the establishment of maternal DNA methylation patterns at LIT1, SNRPN, PEG3 and GTL2. STUDY FUNDING/COMPETING INTERESTS This study was supported by research funds from Agentschap voor Innovatie door Wetenschap en Technologie (IWT-TBM 110680), Wetenschappelijk Fonds Willy Gepts (WFWG 2011) and German Research Foundation (HA 1374/12-2). There are no competing interests.

A prediction model to select PCOS patients suitable for IVM treatment based on anti-Müllerian hormone and antral follicle count

STUDY QUESTION Which baseline patient characteristics can help assisted reproductive technology practitioners to identify patients who are suitable for in-vitro maturation (IVM) treatment? SUMMARY ANSWER In patients with polycystic ovary syndrome (PCOS) who undergo oocyte IVM in a non-hCG-triggered system, circulating anti-Müllerian hormone (AMH), antral follicle count (AFC) and total testosterone are independently related to the number of immature oocytes and hold promise as outcome predictors to guide the patient selection process for IVM. WHAT IS ALREADY KNOWN Patient selection criteria for IVM treatment have been described in normo-ovulatory patients, although patients with PCOS constitute the major target population for IVM. With this study, we assessed the independent predictive value of clinical and endocrine parameters that are related to oocyte yield in patients with PCOS undergoing IVM. STUDY DESIGN, SIZE, DURATION Cohort study involving 124 consecutive patients with PCOS undergoing IVM whose data were prospectively collected. Enrolment took place between January 2010 and January 2012. Only data relating to the first IVM cycle of each patient were included. PARTICIPANTS/MATERIALS, SETTING, METHOD Patients with PCOS underwent oocyte retrieval for IVM after minimal gonadotrophin stimulation and no hCG trigger. Correlation coefficients were calculated to investigate which parameters are related to immature oocyte yield (patients age, BMI, baseline hormonal profile and AMH, AFC). The independence of predictive parameters was tested using multivariate linear regression analysis. Finally, multivariate receiver operating characteristic (ROC) analyses for cumulus oocyte complexes (COC) yield were performed to assess the efficiency of the prediction model to select suitable candidates for IVM. MAIN RESULTS AND THE ROLE OF CHANCE Using multivariate regression analysis, circulating baseline AMH, AFC and baseline total testosterone serum concentration were incorporated into a model to predict the number of COC retrieved in an IVM cycle, with unstandardized coefficients [95% confidence interval (CI)] of 0.03 (0.02-0.03) (P < 0.001), 0.012 (0.008-0.017) (P < 0.001) and 0.37 (0.18-0.57) (P < 0.001), respectively. Logistic regression analysis shows that a prediction model based on AMH and AFC, with unstandardized coefficients (95% CI) of 0.148 (0.03-0.25) (P < 0.001) and 0.034 (-0.003-0.07) (P = 0.025), respectively, is a useful patient selection tool to predict the probability to yield at least eight COCs for IVM in patients with PCOS. In this population, patients with at least eight COC available for IVM have a statistically higher number of embryos of good morphological quality (2.9 ± 2.3; 0.9 ± 0.9; P < 0.001) and cumulative ongoing pregnancy rate [30.4% (24 out of 79); 11% (5 out of 45); P = 0.01] when compared with patients with less than eight COC. ROC curve analysis showed that this prediction model has an area under the curve of 0.7864 (95% CI = 0.6997-0.8732) for the prediction of oocyte yield in IVM. LIMITATIONS, REASONS FOR CAUTION The proposed model has been constructed based on a genuine IVM system, i.e. no hCG trigger was given and none of the oocytes matured in vivo. However, other variables, such as needle type, aspiration technique and whether or not hCG-triggering is used, should be considered as confounding factors. The results of this study have to be confirmed using a second independent validation sample. WIDER IMPLICATIONS OF THE FINDINGS The proposed model could be applied to patients with PCOS after confirmation through a further validation study. STUDY FUNDING/COMPETING INTEREST(S) This study was supported by a research grant by the Institute for the Promotion of Innovation by Science and Technology in Flanders, Project number IWT 070719.

Oocyte maturation and quality: role of cyclic nucleotides

The cyclic nucleotides, cAMP and cGMP, are the key molecules controlling mammalian oocyte meiosis. Their roles in oocyte biology have been at the forefront of oocyte research for decades, and many of the long-standing controversies in relation to the regulation of oocyte meiotic maturation are now resolved. It is now clear that the follicle prevents meiotic resumption through the actions of natriuretic peptides and cGMP - inhibiting the hydrolysis of intra-oocyte cAMP - and that the pre-ovulatory gonadotrophin surge reverses these processes. The gonadotrophin surge also leads to a transient spike in cAMP in the somatic compartment of the follicle. Research over the past two decades has conclusively demonstrated that this surge in cAMP is important for the subsequent developmental capacity of the oocyte. This is important, as oocyte in vitro maturation (IVM) systems practised clinically do not recapitulate this cAMP surge in vitro, possibly accounting for the lower efficiency of IVM compared with clinical IVF. This review particularly focuses on this latter aspect - the role of cAMP/cGMP in the regulation of oocyte quality. We conclude that clinical practice of IVM should reflect this new understanding of the role of cyclic nucleotides, thereby creating a new generation of ART and fertility treatment options.

Human cumulus-enclosed germinal vesicle oocytes from early antral follicles reveal heterogeneous cellular and molecular features associated with in vitro maturation capacity

STUDY QUESTION Are oocyte size, chromatin remodelling, transcriptional activity and mitochondrial distribution in human immature oocytes from early antral follicles retrieved for in vitro maturation (IVM) associated with the acquisition of meiotic competence? SUMMARY ANSWER Oocyte size, chromatin compaction, cessation of RNA synthesis and mitochondria rearrangement around the nucleus are associated with the oocytes potential to resume meiosis in vitro. WHAT IS KNOWN ALREADY Information on oocyte features that confer meiotic competence in human mainly derives from germinal vesicle (GV) oocytes that failed to resume meiosis following an hCG trigger after ovulation induction cycles. Characterization of cumulus-enclosed GV oocytes from small antral follicles prior to IVM provides knowledge on the initial oocyte status and suggests culture requirements in order to promote oocyte competence in vitro. STUDY DESIGN, SIZE, DURATION Prospective collection of 107 oocytes immediately after retrieval (before IVM) and of 293 GV oocytes that had failed to resume meiosis (after IVM). PARTICIPANTS/MATERIALS, SETTING, METHODS Human oocytes were collected from women with polycystic ovary syndrome (PCOS), receiving in total 450 IU of highly purified-hMG for IVM treatment (patients) or who donated oocytes for IVM research (donors). Oocytes at GV-stage were retrieved from follicles <10 mm (range 2-10 mm) diameter, before IVM (oocytes at retrieval) or those that failed to mature after IVM (meiotically incompetent). Oocytes were allocated for either mitochondrial staining, by incubating in mitotracker red and then fixed; or for nascent RNA staining, which was assessed by fluorescent labelling (Click-iT(®) RNA Assay). In every case, oocyte diameter was recorded and chromatin was stained after oocyte fixation. GV-stage oocytes were analysed by confocal laser-scanning microscopy and their characteristics were compared and related to their meiotic competence. MAIN RESULTS AND THE ROLE OF CHANCE Analysis of oocytes at the immature GV-stage revealed that oocytes at retrieval were significantly larger than those that failed to resume meiosis after IVM (112.7 versus 109.6 µm, P < 0.0001). Oocytes assessed at retrieval showed that 50.6% had a condensed chromatin configuration (perinucleolar chromatin rim) and were consistently transcriptionally silent. This rate matched maturation rates in our current in vitro culture system (49%). However, oocytes that had not reinitiated meiosis after 30 h IVM demonstrated, apart of being smaller in diameter, significantly higher rates of dispersed or intermediate chromatin (P = 0.005). Analysis of mitochondrial distribution revealed that many oocytes at retrieval displayed mitochondrial internalization towards the nucleus (12/30) or a perinuclear mitochondrial distribution (6/30). These mitochondrial patterns were observed more rarely in GV incompetent oocytes following 30 h IVM (16/98 and 1/98, respectively). LIMITATIONS, REASONS FOR CAUTION Most of the analyses involved the use of invasive techniques. Hence, despite the fact that these data deliver essential information on the intrinsic oocyte maturational and developmental status, a direct match with embryological outcomes could not be established. WIDER IMPLICATIONS OF THE FINDINGS The evidence described here can aid in tailoring IVM systems in order to promote completion of nuclear and cytoplasmic maturation of unexpanded cumulus-oocyte complexes. STUDY FUNDING/COMPETING INTERESTS This study was supported by research grants by the Institute for the Promotion of Innovation by Science and Technology in Flanders, project numbers IWT 130327 and 110680; the Fund for Research Flanders, project number FWO G.0343.13, the Belgian Foundation Against Cancer (HOPE project) and COOK Medical. None of the authors has any competing interest to declare.

Chromosome constitution of human embryos generated after in vitro maturation including 3-isobutyl-1-methylxanthine in the oocyte collection medium

STUDY QUESTION Do cleavage-stage embryos obtained from oocytes matured in vitro after pre-incubation with a phosphodiesterase inhibitor (IBMX) carry more chromosomal abnormalities than those generated from oocytes matured in vivo? SUMMARY ANSWER The rate and type of chromosomal abnormalities in normally developing cleavage-stage embryos generated with an in vitro maturation (IVM) system including pre-incubation with IBMX are not different from those observed in supernumerary embryos obtained from oocytes matured in vivo. WHAT IS KNOWN ALREADY Very limited information is available about the chromosomal constitution of IVM embryos. Previous studies were carried out using FISH on single biopsied blastomeres or arrested whole embryos and only provided fragmentary information on chromosomal abnormalities in IVM embryos. There is no systematic study of chromosomal abnormalities in all blastomeres of human Day 3 embryos with good morphology. STUDY DESIGN, SIZE, DURATION Between July 2012 and December 2012, 16 young (age <35 years old) egg donors underwent 18 IVM cycles for the generation of research embryos. Eighteen embryos developed to Day 3 and were analysed using array comparative genomic hybridization (aCGH). PARTICIPANTS/MATERIALS, SETTING, METHODS Immature oocytes were retrieved from 2 to 10 mm follicles after mild ovarian stimulation with gonadotrophins but without hCG ovulation trigger. At collection, oocytes were pre-incubated with 3-isobutyl-1-methylxanthine (IBMX), a phosphodiesterase inhibitor and matured in vitro. After IVM culture, mature oocytes were microinjected with sperm from a single donor. Embryos were cultured to Day 3 after ICSI and all blastomeres of 18 good-morphology embryos were collected individually for aCGH. MAIN RESULTS AND THE ROLE OF CHANCE Oocyte maturation rate in vitro was 50.2% (120/239). The mean fertilization rate was 68.3% (82/120) and 30.5% (25/82) of fertilized oocytes developed into a morphologically good quality embryo on Day 3 after ICSI. Of these, 18 embryos that developed well up to Day 3 were analysed using aCGH. Eighty of the 123 blastomeres analysed showed at least one chromosomal abnormality. Three out of eighteen embryos had completely normal cells. A single embryo carried a meiotic abnormality, 11 embryos were mosaic and three were chaotic. Although the aneuploidy data of this study are too limited to allow statistical analysis, these data are comparable to our own published data on the chromosome constitution of whole day 3 and day 4 embryos after conventional ART. LIMITATIONS, REASONS FOR CAUTION Array CGH technology determines relative quantification of chromosomal domains but does not allow for the visualization of chromosomal rearrangements, assessment of ploidy or detection of uniparental isodisomy. Conclusions drawn on segmental abnormalities should be treated with caution. Although the limited number of embryos analysed here precludes firm conclusions, they provide valuable data on possible causes of the reduced potential of IVM embryos. WIDER IMPLICATIONS OF THE FINDINGS This is the first study to describe the complete chromosome complement of all single blastomeres of good-morphology day 3 embryos obtained with IVM (including the presence of IBMX in a pre-incubation medium). The results demonstrate that a high proportion of good-morphology embryos are aneuploid and that there is no obvious increase in aneuploidies as a result of IVM which seems to suggest that the reduced efficiency of IVM technology compared with standard IVF may be accounted for by factors other than aneuploidy, such as cytoplasmic defects or reduced endometrial receptivity. STUDY FUNDING/COMPETING INTERESTS This study was funded by the TBM (Applied Biomedical Research with Societal Finality) programme of the IWT (Agency for Innovation through Science and Technology - Flanders, 110680) and by a Methusalem grant of the Vrije Universiteit Brussel. C.S. is a post-doctoral fellow of the Fund for Scientific Research Flanders (FWO - Vlaanderen). K.J. is a PhD student funded by the FWO. The University of Adelaide owns a patent family associated with IVM technologies that is licensed to Cook Medical. R.B.G. and J.G.T. are inventors. The remaining authors have no conflict of interest to declare.

Addition of highly purified HMG after corifollitropin alfa in antagonist-treated poor ovarian responders: a pilot study

STUDY QUESTION Will sequential administration of highly purified (hp)-HMG after corifollitropin alfa in a GnRH antagonist protocol benefit women with poor ovarian response according to the Bologna criteria? SUMMARY ANSWER Corifollitropin alfa followed by hp-HMG in a GnRH antagonist protocol results in very promising pregnancy rates, albeit only in young (<40 years old) poor ovarian responders fulfilling the Bologna criteria. WHAT IS KNOWN ALREADY Poor ovarian responders fulfilling the Bologna criteria have a very poor prognosis in terms of successful IVF outcome. Although a recent study demonstrated low pregnancy rates in this group of patients after treatment with corifollitropin alfa followed by recombinant FSH in a GnRH antagonist protocol, previous studies showed that the addition of LH activity in 36- to 39-year-old women significantly increases implantation rates. STUDY DESIGN, SIZE, DURATION In this retrospective pilot study, we included poor ovarian responders fulfilling the Bologna criteria treated with a completely novel protocol, with corifollitropin alfa followed by hp-HMG in a GnRH antagonist setting. Overall, 51 patients were treated within a period of 1 year (August 2011-August 2012). PARTICIPANTS/MATERIALS, SETTING, METHODS Patients received 150 μg corifollitropin alfa on second day of the menstrual cycle followed by a fixed daily dose of 0.25 mg of GnRH antagonist on Day 7 of the cycle onwards. On the ninth day of the cycle, a daily fixed dose of 300 IU hp-HMG was administered until the day of ovulation triggering. The primary outcome was ongoing pregnancy rate per patient. MAIN RESULTS AND THE ROLE OF CHANCE Among 47 eligible women, 29 patients were <40 years old and 18 patients were ≥ 40 years old. No differences were observed in endocrine profile, number of cycles with oocyte retrieval (66 versus 67%) and cycles with embryo transfer (62 versus 61%) in women <40 versus ≥ 40 years old, respectively. However, 8 of the 29 women <40 years old had an ongoing pregnancy (28%) compared with 0 of 18 patients who were ≥ 40 years of age (P = 0.017). LIMITATIONS, REASONS FOR CAUTION Owing to the specific retrospective study design, bias cannot be ruled out and these results should not be extrapolated to other treatment protocols for poor ovarian responders. Therefore, caution should be taken when interpreting the results. WIDER IMPLICATIONS OF THE FINDINGS The promising results from this pilot study of corifollitropin alfa followed by hp-HMG stimulation indicate a potential beneficial effect in young poor ovarian responders fulfilling the Bologna criteria. The data provide the rationale for performing a randomized controlled trial to determine if there is sound evidence for a clinical introduction of this protocol. STUDY FUNDING/COMPETING INTEREST(S) No conflicts of interest to declare. No specific funding was received for this study.

Cryopreserved embryo transfer in an artificial cycle: is GnRH agonist down-regulation necessary?

The use of GnRH agonist downregulation in artificial endometrium priming cycles for cryopreserved embryo transfer was retrospectively investigated to establish whether higher live birth rates resulted. Six hundred and ninety-nine patients underwent 1129 artificial endometrium priming cycles for the transfer of cryopreserved embryos between 1 July 2009 and 1 June 2012. Hormonal supplementation with (group A, n = 280 cycles) or without (group B, n = 849 cycles) GnRH agonist co-treatment was given. Live birth rates were comparable between the two groups per started cycle (14.9% [41/275] in group A versus 15.1% [127/839] in group B) or per embryo transfer (17.5% [41/234] in group A versus 17.6% [127/723] in group B). After logistic regression analysis, the only variables that were significantly associated with live birth rates were day of embryo transfer (OR 0.69; 95% CI 0.48 to 0.98) for day 3 versus day 5 embryos, the number of embryos transferred (OR 2.13; 95% CI 1.58 to 2.86) for two embryos versus one embryo transferred and the endometrial thickness on the day of embryo transfer (OR 1.15; 95% CI 1.05 to 1.25). Live birth rates after cryopreserved embryo transfer in artificial cycles did not increase when a GnRH agonist was administered.