Assisted hatching and live births in first-cycle frozen embryo transfers

A multicentre double-blinded randomized controlled trial on the efficacy of laser-assisted hatching in patients with repeated implantation failure undergoing IVF or ICSI

STUDY QUESTION

Does assisted hatching increase the cumulative live birth rate in subfertile couples with repeated implantation failure?

SUMMARY ANSWER

This study showed no evidence of effect for assisted hatching as an add-on in subfertile couples with repeated implantation failure.

WHAT IS KNOWN ALREADY

The efficacy of assisted hatching, with regard to the live birth rate has not been convincingly demonstrated in randomized trials nor meta-analyses. It is suggested though that especially poor prognosis women, e.g. women with repeated implantation failure, might benefit most from assisted hatching.

STUDY DESIGN, SIZE, DURATION

The study was designed as a double-blinded, multicentre randomized controlled superiority trial. In order to demonstrate a statistically significant absolute increase in live birth rate of 10% after assisted hatching, 294 participants needed to be included per treatment arm, being a total of 588 subfertile couples. Participants were included and randomized from November 2012 until November 2017, 297 were allocated to the assisted hatching arm of the study and 295 to the control arm. Block randomization in blocks of 20 participants was applied and randomization was concealed from participants, treating physicians, and laboratory staff involved in the embryo transfer procedure. Ovarian hyperstimulation, oocyte retrieval, laboratory procedures, embryo selection for transfer and cryopreservation, the transfer itself, and luteal support were performed according to local protocols and were identical in both the intervention and control arm of the study with the exception of the assisted hatching procedure which was only performed in the intervention group. The laboratory staff performing the assisted hatching procedure was not involved in the embryo transfer itself.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants were eligible for inclusion in the study after having had either at least two consecutive fresh IVF or ICSI embryo transfers, including the transfer of frozen and thawed embryos originating from those fresh cycles, and which did not result in a pregnancy or as having had at least one fresh IVF or ICSI transfer and at least two frozen embryo transfers with embryos originating from that fresh cycle which did not result in a pregnancy. The study was performed at the laboratory sites of three tertiary referral hospitals and two university medical centres in the Netherlands.

MAIN RESULTS AND THE ROLE OF CHANCE

The cumulative live birth rate per started cycle, including the transfer of fresh and subsequent frozen/thawed embryos if applicable, resulted in 77 live births in the assisted hatching group (n = 297, 25.9%) and 68 live births in the control group (n = 295, 23.1%). This proved to be statistically not significantly different (relative risk: 1.125, 95% CI: 0.847 to 1.494, P = 0.416).

LIMITATIONS, REASONS FOR CAUTION

There was a small cohort of subfertile couples that after not achieving an ongoing pregnancy, still had cryopreserved embryos in storage at the endpoint of the trial, i.e. 1 year after the last randomization. It cannot be excluded that the future transfer of these frozen/thawed embryos increases the cumulative live birth rate in either or both study arms. Next, at the start of this study, there was no international consensus on the definition of repeated implantation failure. Therefore, it cannot be excluded that assisted hatching might be effective in higher order repeated implantation failures.

WIDER IMPLICATIONS OF THE FINDINGS

This study demonstrated no evidence of a statistically significant effect for assisted hatching by increasing live birth rates in subfertile couples with repeated implantation failure, i.e. the couples which, based on meta-analyses, are suggested to benefit most from assisted hatching. It is therefore suggested that assisted hatching should only be offered if information on the absence of evidence of effect is provided, at no extra costs and preferably only in the setting of a clinical trial taking cost-effectiveness into account.

STUDY FUNDING/COMPETING INTEREST(S)

None.

TRIAL REGISTRATION NUMBER

Netherlands Trial Register (NTR 3387, NL 3235, https://www.clinicaltrialregister.nl/nl/trial/26138).

TRIAL REGISTRATION DATE

6 April 2012.

DATE OF FIRST PATIENT’S ENROLMENT

28 November 2012.

Laser-assisted hatching improves pregnancy outcomes in frozen-thawed embryo transfer cycles of cleavage-stage embryos: a large retrospective cohort study with propensity score matching

INTRODUCTION

Laser-assisted hatching (LAH) is a commonly used adjunct technique; however, its effectiveness has not been fully established.

OBJECTIVE

We evaluated the effects of LAH on pregnancy outcomes in frozen-thawed embryo transfer (FET) cycles of cleavage-stage embryos.

MATERIALS AND METHODS

This retrospective study involved 5779 FET cycles performed at the Reproductive and Genetic Center in the Affiliated Hospital of Shandong University of Traditional Chinese Medicine between January 2016 and December 2020. After propensity score matching, 3535 FET cycles were included, out of which 1238 were subjected to LAH while the remaining 2297 cycles were non-LAH (NLAH). The primary outcomes were clinical pregnancy rate (CPR) and live birth rate (LBR) while secondary outcomes included implantation rate (IR), biochemical pregnancy rate (BPR), ectopic pregnancy rate (EPR), pregnancy loss rate (PLR), multiple pregnancy rate (MPL), and monozygotic twinning rate (MTR). Logistic regression analysis was conducted to adjust for possible confounders. Subgroup analysis was also performed based on the endometrial preparation regimen.

RESULTS

The LAH group exhibited a higher LBR, compared to the NLAH group (34.9% vs. 31.4%, OR = 1.185, 95% CI = 1.023, 1.374, P = 0.024). Additionally, the LAH group showed a decreasing trend in PLR and EPR; however, differences were insignificant (P = 0.078, P = 0.063 respectively). Differences in IR (24.6% vs. 24.3%), BPR (41.8% vs. 40.4%), CPR (40.7% vs. 38.3%), MPR (14.1% vs. 17.3%), and MTR (1.4% vs. 1.1%) were insignificant. Subgroup analysis revealed that LAH may be more conducive for pregnancy outcomes in hormone replacement cycles.

CONCLUSIONS

In summary, LAH has an increased chance of achieving live births. However, further prospective studies should be performed to confirm our findings.

Peri-implantation glucocorticoid administration for assisted reproductive technology cycles

BACKGROUND

The use of peri-implantation glucocorticoids has been advocated to improve embryo implantation during assistive reproductive technology (ART) cycles such as in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI). It has been proposed that glucocorticoids may improve the intrauterine environment by acting as immunomodulators to reduce the uterine natural killer (NK) cell count and activity, normalising the cytokine expression profile in the endometrium and by suppression of endometrial inflammation.

OBJECTIVES

To evaluate the effectiveness and safety of glucocorticoids versus no glucocorticoids administered around the time of anticipated implantation in women undergoing IVF or ICSI.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility (CGF) Group specialised register, CENTRAL (now also containing output from two trial registers and CINAHL), MEDLINE and Embase, on 20 December 2021, together with reference checking, contact with experts in the field and relevant conference proceedings to identify additional studies. This review is an update of the review first published in  2007 and last updated in 2012.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing the efficacy of supplementary systemic administration of glucocorticoids in the peri-implantation period with a placebo or no glucocorticoids in subfertile women undergoing IVF or ICSI were included.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. The primary review outcomes were live birth rate and multiple pregnancy.

MAIN RESULTS

We included 16 RCTs (2232 couples analysed). We are uncertain whether glucocorticoids improved live birth rates (odds ratio (OR) 1.37, 95% confidence interval (CI) 0.69 to 2.71; 2 RCTs, n = 366; I² = 7%; very low-certainty evidence). This suggests that if the chance of live birth following no glucocorticoids/placebo is assumed to be 9%, the chance following glucocorticoids would be between 6% and 21%. We are also uncertain whether there was a difference between peri-implantation glucocorticoids on multiple pregnancy rates per couple (OR 0.86, 95% CI 0.33 to 2.20; 4 RCTs, n = 504; I² = 53%; very low-certainty evidence). The I² of 53% may represent moderate statistical heterogeneity and results have to be interpreted with caution. With regard to pregnancy rates, we are uncertain whether there was a difference between ongoing pregnancy rates after glucocorticoids versus no glucocorticoids/placebo (OR 1.19, 95% CI 0.80 to 1.76; 3 RCTs, n = 476; I² = 0%; very low-certainty evidence) and clinical pregnancy rates after glucocorticoids versus no glucocorticoids/placebo (OR 1.17, 95% CI 0.95 to 1.44; 13 RCTs, n = 1967; I² = 0%; low-certainty evidence). This suggests that if the chance of clinical pregnancy following no glucocorticoids/placebo is assumed to be 25%, the chance following glucocorticoids would be between 24% and 32%. Furthermore, we are also uncertain whether peri-implantation glucocorticoids influenced miscarriage rates per couple (OR 1.09, 95% CI 0.63 to 1.87; 6 RCTs, n = 821; I² = 0%; very low-certainty evidence), the incidence of ectopic pregnancies per couple (OR 2.28, 95% CI 0.33 to 15.62; 3 RCTs, n = 320; I² = 0%; very low-certainty evidence) and ovarian hyperstimulation syndrome (OHSS) per couple (OR 1.07, 95% CI 0.60 to 1.90; 3 RCTs, n = 370; I² = 0%; very low-certainty evidence) compared to no glucocorticoids/placebo. The evidence was very low to low certainty: the main limitations were serious risk of bias due to poor reporting of study methods, and serious imprecision.

AUTHORS' CONCLUSIONS

Overall, there was insufficient evidence that administration of peri-implantation glucocorticoids in IVF/ICSI cycles influenced clinical outcomes. These findings were limited to the routine use of glucocorticoids in subfertile women undergoing IVF or ICSI.

The role of assisted hatching in in vitro fertilization: a guideline

There is moderate evidence that assisted hatching does not significantly improve live birth rates in fresh assisted reproductive technology cycles and insufficient evidence for the benefit of assisted hatching in patients with poor prognosis or undergoing frozen embryo transfer cycles. This document replaces the document of the same name published in 2014.

The Current Practice of Assisted Hatching for Embryos in Fertility Centres: a General Survey

At present, there is no standardised protocol for assisted hatching (AH) and the field is beset with contradictory data. We hypothesised that such contradiction may be related to inconsistencies in clinical practice. This study aimed to investigate the application, preferences, and variations of AH in current clinical practice prior to embryo transfer (AHpET) and biopsy (AHpBP). An online voluntary survey, consisted of 25 questions regarding different aspects of AH, was circulated amongst different fertility centres via newsletters between October 2019 and March 2020. One-hundred twenty-nine different fertility centres participated in the survey. AHpBP was widely used (90.6% [48/53]) amongst these centres, especially for trophectoderm biopsy (92.2% [47/51]). In contrast, only 64.6% (73/113) of centres administrated AHpET; the application of AHpET was even lower in UK-based centres (36.6% [15/41]). Although laser pulses have become the predominant technique for AH, significant variation existed in the precise strategy. Zona pellucida (ZP) drilling was the main method for AHpBP, whilst both ZP drilling and ZP thinning were applied equally for AHpET. Furthermore, the ZP manipulation varied widely with regards to the size of the ZP opening and the extension of ZP thinning. This is the first representative survey relating to the current practice of AH. Laser-assisted AH is used extensively, especially for AHpBP. However, there is significant disparity in clinical practice across different centres. Future research should aim to create a standardised protocol for AH to help reduce the evident variation in clinical practice and investigate the true value of AH.

Fresh embryo transfer after in vitro insemination of fresh vs. cryopreserved anonymous donor oocytes: which has a better live birth rate? A Society for Assisted Reproductive Technology Clinic Outcome Reporting System analysis

OBJECTIVE

To determine if transfer of fresh embryos derived from fresh or cryopreserved donor oocytes yields a higher live birth rate.

DESIGN

Historical cohort study.

SETTING

Society for Assisted Reproductive Technology Clinic Outcome Reporting System database.

PATIENT(S)

A total of 24,663 fresh embryo transfer cycles of donor oocytes.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The primary outcome was live births per number of embryos transferred on day 5. The secondary outcomes included number of infants per embryo transfer, surplus embryos cryopreserved, and characterization of US oocyte recipients.

RESULT(S)

A total of 16,073 embryo transfers were from fresh oocytes and 8,590 were from cryopreserved oocytes. Recipient age, body mass index (BMI), gravidity, and parity were similar between the groups. Most recipients were of White non-Hispanic race (66.9%), followed by Asian (13.7%), Black non-Hispanic (9.3%), and Hispanic (7.2%). Fresh oocyte cycles were more likely to use elective single embryo transfer (42.5% vs. 37.8%) or double embryo transfer (53.2% vs. 50.4%) and resulted in more surplus embryos for cryopreservation (4.6 vs. 1.2). The live birth rate from fresh oocytes was 57.5% vs. 49.7% from cryopreserved oocytes. Negative predictors of live birth included the use of cryopreserved oocytes (odds ratio [OR] 0.731, 95% confidence interval [CI] 0.665-0.804), Black non-Hispanic race (OR 0.603, 95% CI 0.517-0.703), Asian race (OR 0.756, 95% CI 0.660-0.867), and increasing recipient BMI (OR 0.982, 95% CI 0.977-0.994) after controlling for recipient age, number of embryos transferred on day 5, and unexplained infertility diagnosis. The proportion of multifetal deliveries was greater in cycles utilizing fresh (26.4%) vs. cryopreserved (20.6%) oocytes.

CONCLUSION(S)

The live birth rate is higher with use of fresh oocytes vs. cryopreserved oocytes in fresh embryo transfer cycles. Negative live birth predictors include recipient Black non-Hispanic or Asian race and increasing BMI.

Laser-assisted hatching zona thinning does not improve the pregnancy outcomes of poor-quality blastocysts in frozen-thawed embryo transfer cycle: a retrospective cohort study

It had been suggested, after facilitating the hatching process, improved pregnancy outcomes could be attained in embryos with thick and hard zona. This study aimed to determine the effect of zona thinning on pregnancy outcomes in poor-quality frozen-thawed blastocysts. This retrospective study included 230 women (≤ 40 years) who underwent frozen embryo transfer of poor-quality blastocysts (scored < 3BB). In total, 105 patients were in the assisted hatching group in which the zona was thinned by laser before transfer and 125 patients were in the control group in which the blastocysts were non-manipulated. Patients' demographics, cycle characteristics, and pregnancy outcomes were compared between the assisted hatching group and the control group. Further, regression analysis was applied to test the correlation between assisted hatching and live birth. All parameters in the patients' demographic characteristics and the cycle's characteristics were not significantly different between two groups. As for pregnancy outcomes, the second trimester pregnancy loss was significantly higher in the assisted hatching group (P = 0.035). Other pregnancy outcomes, including implantation rate, clinical pregnancy rate, biochemical miscarriage rate, the first trimester pregnancy loss, ongoing pregnancy rate, and live birth rate were comparable between two groups. The logistic regression analysis demonstrated no association between live birth and assisted hatching (univariate, OR = 0.787, P > 0.05; multivariate, OR = 0.652, P > 0.05), and the area under the receiver operating characteristic curve of the regression model was almost 0.7. It suggested that zona thinning may not be supposed to perform on poor-quality, frozen-thawed blastocysts. The indications of assisted hatching were still needed to further investigate.

Site specificity of blastocyst hatching significantly influences pregnancy outcomes in mice

Blastocysts hatch from the zona pellucida (ZP) to enable implantation into the uterine endometrial epithelium, but little is known regarding the effect of hatching sites on pregnancy outcomes. Murine hatching embryos were categorized into five groups based on initial trophectoderm projection (TEP)/ZP position corresponding to the inner cell mass center. In blastocysts (3.5 dpc) post-12 hours in vitro culture, TEP rates of A-site (44.4%) and B-site (38.6%) embryos were higher than those of C-site (12.5%) and D-site (3.1%) embryos, while the O-site (1.4%) was the lowest (P < .05). Post-ET A-site (55.6%) and B-site (65.6%) birth rates were higher than those of C-site embryos (21.3%) and controls (P < .05). Furthermore, live birth rate of B-site embryos remained higher than C-site embryos (68.8% vs 31.3%; P < .05) when both were transferred into the same recipients. Different TEP site blastocysts exhibited different implantation competences: the implantation rate of C-site embryos was lower than that of both A- and B-site groups (67.7% vs 84.3% and 83.2%, respectively; P < .05) at 2 days post-ET. C-site embryos also had a distinctly higher ratio of developmental defects (47.5%) than A- and B-site embryos (22.5% and 14.6%, respectively), with implantation failure mainly associated with poor birth rate, a finding corroborated by differential gene expression analysis such as LIF, LIFR, and S100a9. Surprisingly, acidified Tyrode's solution (AAH)-treated B-site blastocysts had a significantly increased birth rate (77.1%) than C-site (55.3%) and controls (43.4%). Site specificity and differential gene expression during embryo hatching can be applied in ART screening. More importantly, assisted hatching by AAH is effective and feasible for improving pregnancy and term development, particularly at the B-site, for humans and in animal husbandry.

Laser-assisted hatching on clinical and neonatal outcomes in patients undergoing single vitrified Blastocyst transfer: A propensity score-matched study

PURPOSE

This study determined the effect of laser-assisted hatching on the clinical and neonatal outcomes of single vitrified blastocyst transfer.

METHODS

From June 2014 to March 2018, 289 matched pairs after propensity score matching were analyzed. During the blastocyst warming procedure, a small section of the zona pellucida area in the empty perivitelline space was sliced off using multiple laser beams. The clinical and neonatal outcomes of the laser-treated group and non-treatment control were analyzed.

RESULTS

In the laser-assisted hatching group, significantly higher rates of clinical pregnancy (40.8% vs 29.4%, P < .01) and live delivery (34.3% vs 22.5%, P < .01) were observed compared to the control group. Other variables such as the average gestational weeks, the sex of the baby, birthweight, or congenital malformations were found to have no significant differences in neonatal outcomes. Moreover, all babies were singleton live births.

CONCLUSIONS

Single vitrified blastocyst transfer treated with laser-assisted hatching increases the live birth rate and has no adverse effects on neonatal outcomes.

ALADDIN study: does assisted hatching of vitrified/warmed blastocysts improve live birth rate? Protocol for a multicentric randomised controlled trial

INTRODUCTION

Recent data suggest a higher clinical pregnancy rate performing assisted hatching (AH) on previously cryopreserved embryos but fail to demonstrate significant effects on live birth rate. However, current evidence is based on studies with a small sample size and may hide a type II error. Moreover, poor attention has been given to the specific effect of AH on frozen/thawed blastocysts. To shed light on this topic, we developed the present protocol for a randomised trial to investigate the benefits of the laser-mediated partial removal of the zona pellucida in vitrified/warmed blastocysts.

METHODS AND ANALYSIS

The pArtiaL zonA pelluciDa removal by assisteD hatchINg of blastocysts (ALADDIN) study is a multicentric prospective comparative study with a parallel randomised controlled design aiming to investigate whether AH performed on warmed blastocysts before embryo transfer can improve live birth rate. Women allocated to the control group will undergo embryo transfer of blastocysts not previously subjected to AH. Two infertility units will be involved in the study. Enrolment of patients will last 18 months with quarterly monitoring and the entire study is foreseen to be closed in 36 months. Secondary outcomes include: proportion of transferred blastocysts/thawed blastocyst, morphological features of blastocysts before embryo transfer, implantation, biochemical pregnancy, clinical pregnancy (ultrasound visible gestational sac), miscarriage, multiple pregnancy, preterm birth (<37 weeks of gestation), obstetrical and neonatal complications and congenital anomaly rates.

ETHICS AND DISSEMINATION

This protocol received a favourable ethical opinion from the Ethical Committee of IRCCS San Raffaele Scientific Institute and the Ethical Committee Area 2 Milan. Each participant will provide written consent to participate and remain encoded during the study. The trial results will be published in peer-reviewed journals and presented at conferences.

TRIAL REGISTRATION NUMBER

NCT03623659; Pre-results.

Higher implantation and live birth rates with laser zona pellucida breaching than thinning in single frozen-thawed blastocyst transfer

While zona pellucida (ZP) breaching of day-3 frozen blastocysts embryos can increase the blastocyst hatching rate, compared with ZP thinning, the pregnancy and implantation rates are similar. The aim of this study was to compare pregnancy outcomes and the risks associated with frozen-thawed blastocysts between laser ZP breaching and laser ZP thinning. For the thinning group, ZP of thawed blastocyst was thinned to a length of 30-40 μm using laser between January 2013 and October 2015. On the other hand, for the breaching group, thawed blastocysts were breached with a 60-80 μm hole in the ZP using laser between November 2015 and April 2018. The implantation rate of ZP breaching (72.7%) was higher than that of ZP thinning (61.8%). In single frozen blastocyst transfer, the implantation rate, clinical pregnancy rate, and live birth rate of ZP breaching (73.9%, 73.9%, 61.8%, respectively) were significantly higher than those of ZP thinning (60.9%, 60.9%, 46.7%, respectively). The abortion rate, preterm birth rate, congenital malformation, birth defects, and birth weight did not significantly differ between the two groups. In conclusion, laser assisted hatching during single frozen blastocyst transfer using ZP breaching exhibit higher implantation, pregnancy, and live birth rates compared with ZP thinning. No significant differences were observed between the two assisted hatching methods in terms of adverse effects on pregnancy and newborns.

Does assisted hatching affect live birth in fresh, first cycle in vitro fertilization in good and poor prognosis patients?

PURPOSE

To assess the effect of assisted hatching (AH) on live birth rate (LBR) in first cycle, fresh in vitro fertilization (IVF) in good and poor prognosis patients.

METHODS

Retrospective cohort using cycles reported to the Society for Assisted Reproductive Technology Clinic Outcomes Reporting System. Live birth rate was compared in women who underwent first cycle, autologous, fresh IVF cycles with (n = 48,858) and without (n = 103,413) AH from 2007 to 2015.

RESULTS

The propensity-weighted LBR was 39.2% with AH versus 43.9% without AH in all patients. The rate difference (RD) with AH was - 4.7% ([CI - 0.053, - 0.040], P < 0.001) with the calculated number needed to harm being 22. AH affected live birth in both good prognosis and poor prognosis patients. The propensity-weighted monozygotic twinning (MZT) rate was 2.3% in patients treated with AH as compared to 1.2% patients that did not receive AH. The RD with AH on MZT in fresh, first IVF cycles was 1.1% ([0.008, 0.014], P < 0.001).

CONCLUSION

AH may affect LBR across all patients and in poor prognosis patients in fresh IVF cycles. Caution should be exercised when applying this technology. More prospective research is needed.

The Effect of Assisted Hatching on Live Birth Rate Following Fresh Embryo Transfer in Advanced Maternal Age

OBJECTIVE

Assisted hatching (AH) was introduced 3 decades ago as an adjunct method to in vitro fertilization (IVF) and embryo transfer (ET) to improve embryo implantation rate. Limited data are available on the effect of AH on live birth rate (LBR) in advanced maternal age. The objective of this study is to investigate the effect of AH on LBR in women aged 40 years and older.

MATERIALS AND METHODS

A retrospective study conducted at a single academic reproductive center. Women aged ≥40 years, who were undergoing their first IVF cycle were included. Laser-assisted hatching was the method used for AH and single or double embryos were transferred. Embryo transfer was performed at the cleavage or blastocyst stage. Separate analysis was performed on each ET stage. Live birth rate was the primary outcome.

RESULTS

A total of 892 patients were included. Of these, 681 women underwent cleavage ET and 211 underwent blastocyst ET. The clinical pregnancy rate in the entire group was 15.3% and the LBR was 10.2%. Baseline and cycle parameters between the AH group and the control group were comparable. Assisted hatching in the cleavage stage was associated with lower clinical pregnancy rate (odds ratio [OR], 0.52; confidence interval [CI], 0.31-0.86; P = .012) and lower LBR (OR, 0.36; CI, 0.19-0.68; P = .001). Assisted hatching did not have any effect on outcomes in blastocyst ET.

CONCLUSION

Assisted hatching does not improve the reproductive outcomes in advanced maternal age. Performing routine AH for the sole indication of advanced maternal age is not clinically justified.