Optimizing the number of blastocyst stage embryos to transfer on day 5 or 6 in women 38 years of age and older: a Society for Assisted Reproductive Technology database study

Day 5 versus Day 6 blastocyst transfers: a systematic review and meta-analysis of clinical outcomes

STUDY QUESTION

Is there a difference in clinical pregnancy and live birth rates (LBRs) between blastocysts developing on Day 5 (D5) and blastocysts developing on Day 6 (D6) following fresh and frozen transfers?

SUMMARY ANSWER

D5 blastocyst transfers (BTs) present higher clinical pregnancy and LBRs than D6 in both fresh and frozen transfers.

WHAT IS KNOWN ALREADY

BT is increasingly popular in assisted reproductive technology (ART) centers today. To our knowledge, no meta-analysis has focused on clinical outcomes in both fresh and frozen BT. Concerning frozen blastocysts, one meta-analysis in 2010 found no significant difference in pregnancy outcomes between D5 and D6 BT. Since then, ART practices have evolved particularly with the wide use of vitrification, and more articles comparing D5 and D6 BT cycles have been published and described conflicting results.

STUDY DESIGN, SIZE, DURATION

Systematic review and meta-analysis of published controlled studies. Searches were conducted from 2005 to February 2018 on MEDLINE and Cochrane Library and from 2005 to May 2017 on EMBASE, Eudract and clinicaltrials.gov, using the following search terms: blastocyst, Day 5, Day 6, pregnancy, implantation, live birth and embryo transfer (ET).

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 47 full-text articles were preselected from 808 references, based on title and abstract and assessed utilizing the Newcastle-Ottowa Quality Assessment Scales. Study selection and data extraction were carried out by two independent reviewers according to Cochrane methods. Random-effect meta-analysis was performed on all data (overall analysis) followed by subgroup analysis (fresh, vitrified/warmed, slow frozen/thawed).

MAIN RESULTS AND THE ROLE OF CHANCE

Data from 29 relevant articles were extracted and integrated in the meta-analysis. Meta-analysis of the 23 studies that reported clinical pregnancy rate (CPR) as an outcome, including overall fresh and/or frozen ET cycles, showed a significantly higher CPR following D5 ET compared with D6 ET (risk ratio (RR) = 1.27, 95% CI: 1.15-1.39, P < 0.001). For CPR, calculated subgroup RRs were 2.38 (95% CI: 1.74-3.24, P < 0.001) for fresh BT; 1.27 (95% CI: 1.16-1.39, P < 0.001) for vitrified/warmed BT; and 1.15 (95% CI: 0.93-1.41, P = 0.20) for slow frozen/thawed BT. LBR was also significantly higher after D5 BT (overall RR = 1.50 (95% CI: 1.32-1.69), P < 0.001). The LBR calculated RRs for subgroups were 1.74 (95% CI: 1.37-2.20, P < 0.001) for fresh BT; 1.38 (95% CI: 1.23-1.56, P < 0.001) for vitrified/warmed BT; and 1.44 (95% CI: 0.70-2.96, P = 0.32) for slow frozen/thawed BT. Sensitivity analysis led to similar results and conclusions: CPR and LBR were significantly higher following D5 compared to D6 BT.

LIMITATIONS, REASONS FOR CAUTION

The validity of meta-analysis results depends mainly on the quality and the number of the published studies available. Indeed, this meta-analysis included no randomized controlled trial (RCT). Slow frozen/thawed subgroups showed substantial heterogeneity.

WIDER IMPLICATIONS OF THE FINDINGS

In regards to the results of this original meta-analysis, ART practitioners should preferably transfer D5 rather than D6 blastocysts in both fresh and frozen cycles. Further RCTs are needed to address the question of whether D6 embryos should be transferred in a fresh or a frozen cycle.

STUDY FUNDING/COMPETING INTEREST(S)

This work was sponsored by an unrestricted grant from GEDEON RICHTER France. The authors have no competing interests to declare.

REGISTRATION NUMBER

CRD42018080151.

Number of supernumerary vitrified blastocysts is positively correlated with implantation and live birth in single-blastocyst embryo transfers

OBJECTIVE

To estimate whether live birth in single-blastocyst transfers is correlated with the number of sibling supernumerary vitrified blastocysts (embryos not transferred) generated from that same cycle.

DESIGN

Retrospective cohort study.

SETTING

A large academic assisted reproduction clinic.

PATIENT(S)

All single-blastocyst transfers in 2010 graded as "good" embryos by Society for Assisted Reproductive Technologies (SART) criteria.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Implantation and live birth.

RESULT(S)

Of the 655 single-blastocyst transfers that met inclusion criteria, implantation occurred in 65% and live birth in 54% of cycles. In chi-square analysis, patients with supernumerary vitrified blastocysts had a statistically higher implantation rate (65% versus 50%) and live-birth rate (56% versus 41%) when compared with patients without supernumerary blastocysts. Univariate logistic regression demonstrated an increase in implantation (OR 1.09; 95% CI, 1.03-1.15) and live birth (OR 1.06; 95% CI, 1.02-1.09) with increasing number of supernumerary blastocysts. Multivariate logistic regression analysis demonstrated that patient age and the number of supernumerary blastocysts were statistically significantly associated with implantation and live birth.

CONCLUSION(S)

The number of supernumerary vitrified blastocysts correlated positively with the odds of implantation and live birth in good quality single-blastocyst transfers. Patients with supernumerary blastocysts are good candidates for single-embryo transfer.

Predicting personalized multiple birth risks after in vitro fertilization-double embryo transfer

OBJECTIVE

To report and evaluate the performance and utility of an approach to predicting IVF-double embryo transfer (DET) multiple birth risks that is evidence-based, clinic-specific, and considers each patient's clinical profile.

DESIGN

Retrospective prediction modeling.

SETTING

An outpatient university-affiliated IVF clinic.

PATIENT(S)

We used boosted tree methods to analyze 2,413 independent IVF-DET treatment cycles that resulted in live births. The IVF cycles were retrieved from a database that comprised more than 33,000 IVF cycles.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The performance of this prediction model, MBP-BIVF, was validated by an independent data set, to evaluate predictive power, discrimination, dynamic range, and reclassification.

RESULT(S)

Multiple birth probabilities ranging from 11.8% to 54.8% were predicted by the model and were significantly different from control predictions in more than half of the patients. The prediction model showed an improvement of 146% in predictive power and 16.0% in discrimination over control. The population standard error was 1.8%.

CONCLUSION(S)

We showed that IVF patients have inherently different risks of multiple birth, even when DET is specified, and this risk can be predicted before ET. The use of clinic-specific prediction models provides an evidence-based and personalized method to counsel patients.

Is cryopreservation of embryos a legitimate surrogate marker of embryo quality in studies of assisted reproductive technology conducted using national databases?

OBJECTIVE

To investigate whether cryopreservation of supernumerary embryos is a good surrogate for embryo quality.

DESIGN

Retrospective study of 6,859 assisted reproductive technology (ART) cycles from women aged <35 years with two fresh day 3 embryos transferred.

SETTING

National Society for Assisted Reproductive Technology Clinic Outcome Reporting System data from 2006-2008.

PATIENT(S)

Women undergoing ART.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Embryo quality (good, fair, or poor), cell number, and live births were compared for cycles with and without cryopreservation, using χ(2) to evaluate statistical significance. The association of freezing with embryo quality was examined using multiple logistic regression after adjusting for confounders (patient age, oocyte yield, intracytoplasmic sperm injection [ICSI], assisted hatching, male factor infertility).

RESULT(S)

Cycles with cryopreservation were more likely to have two embryos of good quality transferred (81.3% vs. 48.5%) and had more 8-cell embryos transferred (76.0% vs. 50.1%). Relative to cycles with two good embryos (good-good), the adjusted odds ratios (OR) for cryopreservation were: good-fair (OR = 0.301, 95% confidence interval [CI] = 0.257-0.354), fair-fair (OR = 0.308, 95% CI = 0.258-0.367), and any poor (OR = 0.058, 95% CI = 0.040-0.083). The live birth rate was 52.4% for cycles with freezing and 40.6% for cycles without.

CONCLUSION(S)

Embryo quality and cell number were both associated with embryo cryopreservation. However, although cryopreservation was a strong marker for good quality, not having cryopreservation did not reliably indicate poor quality, as almost half of those cycles had two good quality embryos.

National collection of embryo morphology data into Society for Assisted Reproductive Technology Clinic Outcomes Reporting System: associations among day 3 cell number, fragmentation and blastomere asymmetry, and live birth rate

OBJECTIVE

To evaluate the validity of collecting day 3 embryo morphology variables into the Society for Assisted Reproductive Technology Clinic Outcomes Reporting System (SART CORS).

DESIGN

Retrospective.

SETTING

National database-SART CORS.

PATIENT(S)

Fresh autologous assisted reproductive technology (ART) cycles from 2006-2007 in which embryos were transferred singly (n=1,020) or in pairs (n=6,508) and embryo morphology was collected.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Relationship between live birth, maternal age, and morphology of transferred day 3 embryos as defined by cell number, fragmentation, and blastomere symmetry. Logistic multiple regressions and receiver operating characteristic curve analyses were applied to determine specificity and sensitivity for correctly classifying embryos as either failures or successes.

RESULT(S)

Live birth rate was positively associated with increasing cell number up to eight cells (<6 cells: 2.9%; 6 cells: 9.6%; 7 cells: 15.5%; 8 cells: 24.3%; and >8 cells: 16.2%), but was negatively associated with maternal age, increasing fragmentation, and asymmetry scores. An area under the receiver operating curve of 0.753 (95% confidence interval 0.740-0.766) was derived, with a sensitivity of 45.0%, a specificity of 83.2%, and 76.4% of embryos being correctly classified with a cutoff probability of 0.3.

CONCLUSION(S)

This analysis provides support for the validity of collecting morphology fields for day 3 embryos into SART CORS. Standardization of morphology collections will assist in controlling for embryo quality in future database analyses.

Cycle 1 as predictor of assisted reproductive technology treatment outcome over multiple cycles: an analysis of linked cycles from the Society for Assisted Reproductive Technology Clinic Outcomes Reporting System online database

OBJECTIVE

To determine whether the first cycle of assisted reproductive technology (ART) predicts treatment course and outcome.

DESIGN

Retrospective study of linked cycles.

SETTING

Society for Assisted Reproductive Technology Clinic Outcome Reporting System database.

PATIENT(S)

A total of 6,352 ART patients residing or treated in Massachusetts with first treatment cycle in 2004-2005 using fresh, autologous oocytes and no prior ART. Women were categorized by first cycle as follows: Group I, no retrieval; Group II, retrieval, no transfer; Group III, transfer, no embryo cryopreservation; Group IV, transfer plus cryopreservation; and Group V, all embryos cryopreserved.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Cumulative live-birth delivery per woman, use of donor eggs, intracytoplasmic sperm injection (ICSI), or frozen embryo transfers (FET).

RESULT(S)

Groups differed in age, baseline FSH level, prior gravidity, diagnosis, and failure to return for Cycle 2. Live-birth delivery per woman for groups I through V for women with no delivery in Cycle I were 32.1%, 35.9%, 40.1%, 53.4%, and 51.3%, respectively. Groups I and II were more likely to subsequently use donor eggs (14.5% and 10.9%). Group II had the highest use of ICSI (73.3%); Group III had the lowest use of FET (8.9%).

CONCLUSION(S)

Course of treatment in the first ART cycle is related to different cumulative live-birth delivery rates and eventual use of donor egg, ICSI, and FET.

Can prematurity risk in twin pregnancies after in vitro fertilization be predicted? A retrospective study

BACKGROUND

Assisted reproduction (ART) contributes to world-wide increases of twin pregnancies, in turn raising prematurity risks. Whether characteristics of ART cycles, resulting in twin gestations, can predict prematurity risks was the subject of this study.

METHODS

One-hundred-and-six women, ages 20 to 39 years, with consecutive dichorionic-diamniotic (DC/DA) twin gestations were retrospectively investigated. All pregnancies investigated followed fresh ART cycles, with use of autologous gamets, and were delivered at a university-based high-risk, maternal-fetal medicine unit. Only premature deliveries (i.e., <37.0 weeks gestational age), with viable neonate(s) of > or = 500 grams, were considered for analysis.

RESULTS

After 1.8 +/- 1.2 ART cycles, 11.0 +/- 5.4 oocytes were retrieved and 2.4 +/- 0.9 embryos transferred in 106 women aged 31.6 +/- 4.2 years. Indications for ART treatment were male factor in 51.9%, female infertility in 27.4% and combined infertility in 20.8%. Though maternal age significantly influenced prematurity risk (p < 0.05), paternal age, maternal body mass index, indications for fertility treatment, number of previous ART attempts, oocytes retrieved or embryos transferred, as well as stimulation protocols and previous ART pregnancies, were not associated with gestational duration in twin pregnancies.

SUMMARY

Except for female age, baseline and ART cycle characteristics do not allow for prediction of prematurity risk in dichorionic twin gestations after assisted reproduction.