The clinical outcomes of day 3 4-cell embryos after extended in vitro culture

Clinical Outcome of Day-3 Cleavage Slow-Growing Embryos at Different Cleavage Rates after Overnight Culture: A Cohort Retrospective Study

INTRODUCTION

We explored the association between clinical outcomes and the cleavage rate of day-3 cleavage slow-growing embryos after overnight culture.

METHODS

The data collected from 303 frozen embryo transfer (FET) cycles with 606 4-cell or 5-cell embryos cultured overnight (18-22 h) after thawing were analyzed. Based on the growth rate after the overnight culture, the embryos were divided into three groups: no embryo reaching eight cells (Group I), either one of the two embryos reaching eight cells (Group II), and both two embryos reaching eight cells or more (Group III). A statistical analysis of the different clinical outcomes from the three groups was performed.

RESULTS

Biochemical pregnancy rate (OR 3.22; p = 0.001), implantation rate (OR 2.44; p = 0.002), clinical pregnancy rate (OR 3.04; p = 0.001), ongoing pregnancy rate (OR 3.14; p = 0.001), and live birth rate (OR 2.78; p = 0.004) were significantly higher in Group III as compared to Group I. Group II had a significantly higher biochemical pregnancy rate (OR 2.02; p = 0.013) and implantation rate (OR 1.77; p = 0.019) than Group I.

CONCLUSIONS

The capability of day-3 cleavage slow-growing embryos to reach eight cells, especially that of two embryos reaching eight cells by overnight culture, appear to result in a better pregnancy outcome.

What is optimal timing of warming for transferring vitrified cleavage stage of day 3 slow-growing embryos? A cohort retrospective study

PURPOSE

To evaluate optimal warming time, the early warming or the routine warming time, for transferring vitrified-warmed and cultured overnight cleavage stage of the slow-growing embryos on day 3 in frozen embryo transfer (FET) cycle.

METHODS

This was a retrospective cohort study from January 2017 to July 2018. A total of 705 FET patients aged < 40 years were included and 1486 embryos were formed, of which 1366 embryos were eventually transferred.

RESULTS

For slow-growing embryos, the clinical pregnancy rate of early warming group [152/468 (32.5%)] was significantly higher than that of routine warming group (55/235 (23.4%)) [OR 1.39 (CI 1.06-1.81), p = 0.01], while there was no statistically significant difference in pregnancy loss in early warming group [39/170 (22.9%)] versus in routine warming group [16/62 (25.8%)] [OR 0.89 (CI 0.53-1.47), p = 0.65].

CONCLUSION

For slow-growing embryos, higher pregnancy outcomes were shown in early warming strategy as compared to the routine warming, which suggested that the improvement of endometrium-embryo synchronism may correct the time difference brought by the slow-growing embryos.

The Effects of Different Post-thawed Culture Periods on Clinical Outcomes in Frozen Embryo Transfer Cycle

The purpose of this study is to evaluate the effects of different post-thawed culture periods on the clinical outcomes. 9381 frozen embryo transfer (FET) cycles were divided into three groups according to female age: < 35, 35-39, and > 39 years, and two groups depending on post-thawed culture period before transfer: short culture (2-3 h) group (S) and long culture (18-20 h) group (L). According to the increment number of post-thawed embryos, the L group divided into three groups: ≤ 2, one ≤ 2 and the other > 2, and > 2 groups. Pregnancy outcomes included the implantation rate (IR), clinical pregnancy rate (CPR), multiple pregnancy rate (MPR), live birth rate (LBR), and neonatal characteristics. Long post-thawed culture caused a significant increase in the IR, CPR, MPR, and LBR (p = 0.000, 0.004, 0.037, and 0.001; CI = 1.06-1.194, 1.042-1.237, 1.008-1.254, and 1.054-1.245, respectively), and blastomere increment number also had a significant effect on IR, CPR, MPR, and LBR (p = 0.000, 0.000, 0.000, and 0.000, respectively). No significant differences were present in neonatal characteristics between the two post-thawed culture groups. Singleton group had a higher average gestational age and birthweight as well as a lower cesarean section rate, preterm labor rate, and low birthweight rate than twins group. Long post-thawed culture was associated with higher IR, CPR, MPR, and LBR, and transferring a well-developed embryo after long post-thawed culture might be a viable embryo transfer strategy to decrease MPR while maintaining CPR and LBR.

Blastocyst transfer after extended culture of cryopreserved cleavage embryos improves in vitro fertilization cycle outcomes

Cryopreserved blastocyst embryo transfer has been reported to result in better pregnancy outcomes than those by cleavage embryo transfer. Women who had previously failed in the cleavage-stage embryo transfer, underwent extended culture of their warmed cleavage embryos to the blastocyst stage, thereby improving cryopreserved embryo transfer (CET) outcomes, although the ability of embryos to reach the extended blastocyst as well as the value of the prolonged culture was limited. This study aimed to investigate the effectiveness of blastocyst transfer by extending the culture of vitrified-warmed cleavage embryos. CET cycles were collected from January 2018 to June 2020. Pregnancy outcomes were analyzed and compared between three groups: day 2 embryo transfer using cryopreserved embryos (D2 CET), blastocyst transfer (D5 CET), and extended culture vitrified day 2 embryo transfer (D2-5 CET). A total of 52.77% of vitrified-warmed cleavage embryos developed into blastocysts in D2-5 CET group. Although D2-5 CET had a lower number of transferred embryos and grade A embryos, the pregnancy outcomes were significantly better than those in D2 CET, with respect to hCG positivity, clinical pregnancy and implantation rates (59.62% vs. 24.64%, 46.15% vs. 21.71%, 27.18% vs. 9.09%, respectively, P < 0.05). There were no significant different outcomes between the D2-5 CET and D5 CET groups. This study demonstrated a way of achieving better pregnancy outcomes in 8CET cycles by means of extended culture to blastocysts in patients with vitrified cleavage embryo failure.

Improving the clinical outcomes by extended culture of day 3 embryos with low blastomere number to blastocyst stage following frozen-thawed embryo transfer

Purpose

This study aimed to investigate whether the extended culture of day 3 (D3) embryos with low blastomere number to blastocyst following frozen–thawed embryo transfer improved the clinical outcomes.

Methods

This was a retrospective study of clinical data of women undergoing in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) cycles in the Tangdu Hospital. The patients were divided into groups with 4–5, 6, 7–9 and > 9 cells based on the blastomere number of D3 embryos. The clinical outcomes were compared.

Results

In fresh transfer cycles, the implantation and clinical pregnancy rates significantly decreased, while the abortion rate significantly increased in the groups with 4–5 and 6 cells compared with those with 7–9 and > 9 cells. In frozen–thawed transfer cycles, the clinical pregnancy and implantation rates for a single blastocyst transfer cycle showed no significant differences in the groups with 4–5 and 6 cells compared with those with 7–9 and > 9 cells. However, the abortion rate was significantly higher in the group with 4–5 cells than in that with 7–9 and > 9 cells. In the double blastocyst transfer cycle, the clinical pregnancy rate showed no significant differences among the groups with 4–5, 6, and 7–9 cells.

Conclusion

The implantation and clinical pregnancy rates of D3 embryos with 6 cells significantly decreased; these embryos were not considered as high-quality embryos. Extended culture of D3 embryos with ≤ 6 blastomeres to blastocysts, particularly 6-cell embryos, resulted in a similar clinical pregnancy rate as that of blastocysts derived from D3 embryos with ≥ 7 blastomeres.

The Valuable Reference of Live Birth Rate in the Single Vitrified-Warmed BB/BC/CB Blastocyst Transfer: The Cleavage-Stage Embryo Quality and Embryo Development Speed

Background

It is unclear whether we should focus attention on cleavage-stage embryo quality and embryo development speed when transferring single particular grade vitrified-warmed blastocysts, especially poor-quality blastocysts (grade “C”).

Method

This retrospective study considered 3386 single vitrified-warmed blastocyst transfer cycles from January 2010 to December 2017. They were divided into group 1 (AA/AB/BA, n = 374), group 2 (BB, n = 1789), group 3 (BC, n = 901), and group 4 (CB, n = 322). The effects of cleavage-stage embryo quality and embryo development speed were measured in terms of clinical pregnancy and live birth rates in each group.

Results

Pregnancy outcomes showed a worsening trend from groups 1 to 4; the proportion of embryos with better cleavage-stage quality and faster development speed decreased. In group 1, only the blastocyst expansion degree 3 was a negative factor in the clinical pregnancy rate (odds ratio (OR) [95% confidence interval (CI)]: 0.233 [0.091–0.595]) and live birth rate (0.280 [0.093–0.884]). In the other groups (BB, BC, and CB), blastocysts frozen on day 5 had significantly better clinical pregnancy outcomes than those frozen on day 6: 1.373 [1.095–1.722] for group 2, 1.523 [1.055–2.197] for group 3, and 3.627 [1.715–7.671] for group 4. The live birth rate was 1.342 [1.060–1.700] for group 2, 1.544 [1.058–2.253] in group 3, and 3.202 [1.509–6.795] in group 4, all Ps < 0.05). The degree of blastocoel expansion three for clinical pregnancy rate in group 2 (0.350 [0.135–0.906], P < 0.05) and day 3 blastomere number (>7) for live birth rate in group 4 (2.455 [1.190–5.063], P < 0.05) were two important factors.

Conclusion

We should consider choosing BB/BC/CB grade blastocysts frozen on day 5, CB grade blastocysts with day 3 blastomere numbers (>7), and AA/AB/BA grade blastocysts with degrees of expansion (≥4) to obtain better pregnancy outcomes.

Impact of Day 7 Blastocyst Transfer on Obstetric and Perinatal Outcome of Singletons Born After Vitrified-Warmed Embryo Transfer

BACKGROUND

Extended embryo culture has been reported to affect perinatal outcome regarding higher risks of large for gestational age (LGA) and preterm birth (PTB) yet decreased risk of small for gestational age (SGA). However, existing data about the obstetric outcome and the safety for offspring resulting from the transfer of day 7 blastocysts is rare.

OBJECTIVES

To compare obstetric and perinatal outcome using embryos vitrified on day 7 with those vitrified on day 3, day 5, and day 6.

METHODS

Data were collected from 4489 infertile women who gave birth to live-born singletons after vitrified-warmed embryo transfer cycles from January 1, 2006 to December 31, 2017. Singletons were compared depending on the age of embryos. Main perinatal outcome parameters included PTB (gestational age < 37 weeks), very PTB (VPTB, gestational age < 32 weeks), LGA (birthweights > 90th percentiles), and SGA (birthweights < 10th percentiles). Obstetric outcomes included gestational diabetes (GDM), pregnancy-induced hypertension (PIH), preterm premature rupture of membranes (PPROM), pre-eclampsia, placenta previa, placental abruption, and postpartum hemorrhage. Propensity score matching (PSM) was used to adjust the confounding factors across groups and then analyze the association between in vitro culture period and the outcome measures.

RESULTS

After PSM, the transfer of day 7 blastocysts was associated with higher birth weight Z-scores and increased incidence of very large for gestational age (VLGA) compared with the transfer of day 3 cleavage-stage embryos while the incidence of PTB, low birth weight (LBW), SGA did not reach statistical significance. Moreover, comparable perinatal outcome was found in the comparison of day 7 vs. day 5 and day 7 vs. day 6. Day 7 blastocysts did not result in adverse obstetric outcome compared with day 3, day 5, and day 6 embryos, respectively.

CONCLUSION

In vitrified-warmed transfer cycles, day 7 blastocysts were associated with adverse perinatal outcome regarding higher risk of VLGA compared with day 3 cleavage-stage embryo, while blastocysts with diverse growth rates embrace similar developmental viability regardless of blastocysts vitrified on day 5, day 6, or day 7.

Improvement of pregnancy outcome by extending embryo culture in IVF-ET during clinical application

PURPOSE

The purpose of this study is to investigate the application value of the extended embryo culture for 7-8 h in day 3 morning during IVF-ET process.

METHODS

Embryos were retrospectively assessed during 08:00-09:00 on the morning of day 3 in the control group, and were assessed once again at 16:00 in the afternoon in the extended culture (EC) group. The embryos with good developmental potential were preferentially selected to transfer. The cumulative pregnancy outcomes were analyzed in one oocyte retrieval cycle.

RESULTS

Similar proportions were found in the rates of cumulative clinical pregnancy, cumulative live birth, and the perinatal/neonatal outcomes per oocyte retrieval cycle (P > 0.05). But higher total clinical pregnancy rate, higher total implantation rate, and lower total abortion rate were obtained in the EC group (P < 0.05). After EC, 53.58% of the embryos were able to continue to develop. The transferred embryos were mainly composed of ≥ 8-cell embryos (75.90%) in the EC group and ≤ 8-cell embryos (82.92%) in the control group. Interestingly, the implantation rates were increasingly improved with the increasing blastomere number up to 56.31% at the morula stage in the EC group, while they were limited to 32.33% at 8-cell stage in the control group.

CONCLUSIONS

The extended culture of day 3 embryos for 7-8 h not only reduced the risk of IVF-ET treatment compared to blastocyst culture through another 2-3 days, but also improved the clinical outcomes and the efficiency of every transferred cycle and every transferred embryo.

Developmentally delayed cleavage-stage embryos maintain comparable implantation rates in frozen embryo transfers

PURPOSE

In fresh IVF cycles, embryos reaching the eight-cell stage on day 3 of development are thought to have a higher chance of implantation than those reaching this stage on day 4. To determine whether this difference persists after cryopreservation, we compared pregnancy and implantation rates between frozen embryo transfer (FET) cycles using delayed cleavage-stage embryos (cryopreserved day 4) and normal cleavage-stage embryos (cryopreserved day 3).

METHODS

Participants underwent FET between 2008 and 2012 using embryos cryopreserved on either day 3 (n = 76) or day 4 (n = 48), depending on the length of time needed to achieve the eight-cell stage. All embryos, regardless of day of cryopreservation, were thawed and transferred on the 4th day of vaginal progesterone following endometrial preparation with oral estradiol. Chi-square and Mann-Whitney U tests were used to compare patient demographics and cycle outcomes.

RESULTS

More women in the day 4 group had diminished ovarian reserve (44 vs 16 %, p = 0.003). Pregnancy outcomes in preceding fresh cycles were not different between the two groups. Pregnancy, implantation, and live birth rates following FET did not differ between the day 3 and day 4 groups.

CONCLUSIONS

This is the first study to address outcomes using day 3 versus day 4 cryopreserved embryos. Despite a higher prevalence of diminished ovarian reserve (DOR) in the day 4 group, delayed cleavage-stage embryos utilized in FET cycles performed as well as embryos growing at the normal rate, suggesting delayed embryo development does not affect embryo implantation as long as endometrial synchrony is maintained.

Prognostic value of growth of 4-cell embryos on the day of transfer in fresh IVF-ET cycles

PURPOSE

To investigate the prognostic value of growth of 4-cell embryos on the day of transfer in determining clinical pregnancy and live birth rates after fresh in vitro fertilization (IVF)-embryo transfer (ET) cycles.

METHODS

Retrospective cohort study of all patients between January 2008 and January 2013 initiating fresh IVF-ET cycles resulting in embryos that were not more than 4 cells 72 h after oocyte retrieval in the morning of their transfer. Patients were stratified into 2 groups based on whether embryos did or did not grow more than the 4-cell stage on the afternoon of ET. The odds of clinical pregnancy and live birth were considered as primary outcomes. Student's t-tests and Chi-square (χ2) tests were used as indicated, with logistic regression controlling for maternal age and number of embryos transferred.

RESULTS

Three hundred forty three patients were identified for inclusion: 165 and 178 patients had 4-cell embryos with and without growth on the afternoon of ET, respectively. The demographic and baseline IVF cycle characteristics of the study cohort were comparable. Patients with embryo growth had higher clinical pregnancy (13.9 % vs. 4.49 %) and live birth (10.9 % vs. 3.37 %) rates compared to patients without embryo growth. This represented an overall increased odds of clinical pregnancy [Odds ratio (OR) = 3.44; 95 % Confidence Intervals (CI) 1.49-7.93; P = 0.004)] and live birth (OR = 3.51; 95 % CI 1.36-9.07; P = 0.01). The increased odds remained unchanged after adjusting for maternal age and number of embryos transferred.

CONCLUSIONS

Transfer of 4-cell embryos 3 days after oocyte retrieval can result in clinical pregnancies and live births, albeit at a low rate. Growth of an embryo more than the 4-cell stage on the afternoon of ET may serve as a positive prognostic factor for IVF-ET cycle outcome.