Selected single blastocyst transfers maintained pregnancy outcome and eliminated multiple pregnancies

Comparisons of benefits and risks of single embryo transfer versus double embryo transfer: a systematic review and meta-analysis

BACKGROUND

Evidence referring to the trade-offs between the benefits and risks of single embryo transfer (SET) versus double embryo transfer (DET) following assisted reproduction technology are insufficient, especially for those women with a defined embryo quality or advanced age.

METHODS

A systematic review and meta-analysis was conducted according to PRISMA guidelines. PubMed, EMBASE, Cochrane Library and ClinicalTrials.gov were searched based on established search strategy from inception through February 2021. Pre-specified primary outcomes were live birth rate (LBR) and multiple pregnancy rate (MPR). Odds ratio (OR) with 95% confidence interval (CI) were pooled by a random-effects model using R version 4.1.0.

RESULTS

Eighty-five studies (14 randomized controlled trials and 71 observational studies) were eligible. Compared with DET, SET decreased the probability of a live birth (OR = 0.78, 95% CI: 0.71-0.85, P < 0.001, n = 62), and lowered the rate of multiple pregnancy (0.05, 0.04-0.06, P < 0.001, n = 45). In the sub-analyses of age stratification, both the differences of LBR (0.87, 0.54-1.40, P = 0.565, n = 4) and MPR (0.34, 0.06-2.03, P = 0.236, n = 3) between SET and DET groups became insignificant in patients aged ≥40 years. No significant difference in LBR for single GQE versus two embryos of mixed quality [GQE + PQE (non-good quality embryo)] (0.99, 0.77-1.27, P = 0.915, n = 8), nor any difference of MPR in single PQE versus two PQEs (0.23, 0.04-1.49, P = 0.123, n = 6). Moreover, women who conceived through SET were associated with lower risks of poor outcomes, including cesarean section (0.64, 0.43-0.94), antepartum haemorrhage (0.35, 0.15-0.82), preterm birth (0.25, 0.21-0.30), low birth weight (0.20, 0.16-0.25), Apgar1 < 7 rate (0.12, 0.02-0.93) or neonatal intensive care unit admission (0.30, 0.14-0.66) than those following DET.

CONCLUSIONS

In women aged < 40 years or if any GQE is available, SET should be incorporated into clinical practice. While in the absence of GQEs, DET may be preferable. However, for elderly women aged ≥40 years, current evidence is not enough to recommend an appropriate number of embryo transfer. The findings need to be further confirmed.

An elective single cleavage embryo transfer strategy to minimize twin live birth rate based on a prediction model from double cleavage embryos transfer patients

OBJECTIVE

To minimize twin birth rate by establishing an elective single cleavage embryo transfer strategy based on a twin live birth prediction model from fresh double cleavage embryos transfer (cleavage DET) patients.

METHODS

A total of 2478 patients underwent fresh cleavage DET in Nanjing Tower Hospital were enrolled to establish the twin live birth prediction model by logistic regression analysis and the cutoff value was calculated by ROC curve. Another 300 fresh cleavage DET patients and 550 cleavage single-embryo transfer (SET) patients were selected to testify the sensitivity, specificity and usefulness of this model.

RESULTS

The twin live birth probability (TLBP) = e^X /(e^X + 1), e is a natural logarithm, X = -1.763 - (0.319 × female age) + (0.329 × endometrial thickness) + (0.282 × the number of transferred top embryos) - (0.314 × previous transfer times), and the cutoff value of TLBP was 24.2%. The sensitivity of this model for predicting twin live birth was 75.6%, while the specificity was 52.5% in the external validation of 300 DET patients. Furthermore, the validation of 550 SET patients showed that the live birth rate of TLBP value positive patients was significantly higher than that in negative patients (54.3% vs. 35.5%, p < .001). When adopted an elective single cleavage embryo transfer strategy, the patients with a positive TLBP value choose SET, while still undergo DET who with a negative TLBP value, the live birth rate would maintain as 56.7%; however, the twin birth rate would significantly decline to 7.4%.

CONCLUSION

Female age, endometrial thickness, the number of transferred top embryos and previous embryo transfer times were critical variables for the twin live birth prediction model. An elective single cleavage embryo transfer strategy according to this model can maintain the relatively high live birth rate, meanwhile get the acceptable low twin birth rate.

Effect on clinical and neonatal outcomes of blastocelic microsuction prior to vitrification

PURPOSE

Microsuction (MS) is a technique for mechanically emptying fluid from blastocele using a microneedle. In this study, we evaluated the improvement in clinical and neonatal outcomes of vitrified blastocyst transfer programs when MS of blastocelic fluid was used before vitrification.

METHODS

This was a retrospective study based on data collected between March 2014 and August 2016. A total of 317 blastocysts obtained from 211 patients were analyzed. The blastocelic fluid of expanded blastocysts was aspirated completely, and blastocysts were collapsed prior to vitrification. Clinical and neonatal outcomes of warmed blastocysts were compared.

RESULTS

The survival rate of the MS blastocyst was significantly higher compared with the nontreatment control (98.7% vs 89.3%, OR: 9.34, 95% CI: 2.35-36.8, P < 0.01). The rates of implantation and live birth were higher in the MS group than in the control group, but the differences were not significant. There were no differences in gestational age, birthweight, proportion of male babies, rates of cesarean section, and congenital abnormalities.

CONCLUSION

The MS procedure improved blastocyst survival and had little effect on further embryo development after warming.

Developmental capacity and implantation potential of the embryos with multinucleated blastomeres

The presence of multinucleated blastomeres (MNBs) in embryos is associated with poor developmental competence in assisted reproductive technologies. This phenomenon is observed not only in humans but also in other animal species. The purpose of the present study was to investigate the characteristics of embryos with MNBs (MNB embryos) that could be utilized in embryo transfer. The developmental rate of MNB embryos to the blastocyst stage (50.8%) was significantly lower than that of normal embryos (73.3%) (P < 0.05). The clinical pregnancy rates of fresh embryo transfer (ET) using day 2 or day 3 embryos were significantly lower in MNB embryos (5.1%) compared with normal embryos (24.0%) (P < 0.05). In the case of frozen-thawed ET using a single vitrified/warmed blastocyst, however, the clinical pregnancy rate of MNB embryos was close to that of normal embryos (59.1% vs. 52.8%). Thus, the findings of the present study suggest that the frozen-thawed ET of MNB embryos might improve the potential for implantation followed by successful pregnancy.

Elective single embryo transfer: Comparison of blastocyst and cleavage-stage embryo transfer

Objective:   Blastocysts are reportedly suitable for preventing multiple pregnancies as a result of the high implantation rate per embryo. The present study compared clinical results for elective single embryo transfer (ET) between blastocysts and cleavage-stage embryos in order to ascertain the usefulness of blastocyst culturing in single ET. Methods:   Between January 2002 and December 2004, conventional in vitro fertilization ET and/or intracytoplasmic sperm injection was carried out for single ET in 86 cycles, to prevent multiple pregnancies (for medical reasons or because of patient wishes). Results:   Among the 80 cycles in which a fresh embryo was transferred, pregnancy/implantation rates per ET were 35.3% for day 2/3 ET and 50.0% for day 5 ET, and pregnancy/implantation rates per oocyte retrieval were 35.3% for day 2/3 ET and 44.2% for day 5 ET. Ongoing pregnancy/delivery rates per oocyte retrieval were 32.4% for day 2/3 ET and 38.5% for day 5 ET. Monozygotic twinning occurred in one case of day 5 ET. Conclusions:   Pregnancy rates per single ET tended to be higher for day 5 ET than for day 2/3 ET. However, no marked differences were identified in ongoing pregnancy/delivery rates per oocyte retrieval between groups. (Reprod Med Biol 2005; 4: 197-201).

Pregnancy rate, multiple pregnancy rate, and embryo quality: Clues for single blastocyst transfer from double blastocyst transfer in an unselected population

Objective:  Minimizing multiple pregnancy is a priority in assisted reproduction. As implantation rates are critical to success and reduce multiple pregnancy, we investigated whether blastocyst grade determined implantation rate following double blastocyst transfer in unselected cases. Materials and Methods:  We studied 69 three-cleavage stage embryo transfers and 64 two-blastocyst transfers. Two blastocysts, or one when two blastocysts were not available, were transfered after evaluating the grade of blastocysts. The difference in pregnancy and implantation rates to patient age, the number of retrieved oocytes and grade of blastocysts were analyzed. Results:  Blastocyst and grade 3AA rates per fertilized egg were 50.3% and 26.0%, respectively. Following two-blastocyst transfer, pregnancy rate per transfer, implantation rate per embryo, and multiple pregnancy rate per pregnancy were 39.1%, 26.5%, and 24.0%, respectively. Two-blastocyst transfer achieved implantation more often than three-cleavage-stage embryo transfer, but did not reduce multiple pregnancy. Pregnancy, implantation, and multiple pregnancy rates did not reflect maternal age. Higher pregnancy and implantation rates per transfer were attained for with six or more oocytes retrieved or transfer of two-blastocyst graded 3AA or higher especially when two or more blastocysts graded 3AA or higher are available, but the latter showed a high multiple pregnancy rate (38.5%). Conclusions:  Single embryo transfer could be carried out when two or more blastocysts of grade 3AA or higher have been developed. (Reprod Med Biol 2005; 4: 153-160).