Improved clinical outcomes for in vitro fertilization with delay of embryo transfer from 48 to 72 hours after oocyte retrieval: use of glucose- and phosphate-free media

Comparison of day 2 and overnight day 3 frozen embryo transfers: A prospective randomized controlled trial

In certain patients cleavage stage embryos may be preferred. The relationship between an additional day in culture and pregnancy outcomes is not well established. We aimed to compare outcomes of day 2 versus overnight day 3 frozen embryo transfer (FET). In this randomized controlled trial, patients with day 2 cryopreserved embryos were allocated to two groups. In group A embryos were transferred on day 2, the same day of thawing. In group B embryos were transferred one day after thawing, on day 3 after overnight incubation. Out of 410 patients eligible, 92 were recruited. Finally, 72 patients participated, 39 in group A and 33 in group B. No significant difference in implantation (11 % in group A and 14 % in group B, p = 0.81), clinical pregnancy (18 % in group A and 21 % in group B, p = 0.73) or live birth rates (13 % in group A and 18 % in group B, p = 0.53) was found. To conclude, no significant difference in reproductive outcomes was found when comparing patients with day 2 or overnight day 3 FET. Considering published data on blastocyst transfer, cleavage stage ET may still be a relevant option and the decision between day 2 or overnight day 3 ET depends on patients' and physicians' preference and recommendation.

The effect of day 2 versus day 3 embryo transfer on early pregnancy outcomes in women with a low yield of fertilized oocytes

PURPOSE

To evaluate the differences in implantation and pregnancy rates when embryo transfer occurs on D2 versus D3 in women with a low yield of fertilized oocytes.

METHODS

A total of 156 IVF/ICSI cycles from 141 women at an academic fertility center were analyzed in a retrospective fashion. Women with a low number of fertilized oocytes (≤ 2 two pronuclei (2PN) stage zygotes) who had their fresh embryo transfer on D2 or D3 were included in the study. Positive pregnancy test per IVF cycle (PPT), clinical pregnancy rate (CPR), spontaneous abortion rate (SABR), and implantation rate (IMPR) were the main outcome measures assessed. Mann-Whitney U test and χ² test were used as appropriate. A generalized linear mixed effect model adjusted for relevant covariates was conducted. P < 0.05 was considered significant.

RESULTS

Patients having their embryo transfer on D2, when compared to those who had a D3 embryo transfer, experienced similar PPT [30.8 vs. 28.2%, respectively; adjusted OR (95%CI): 0.49 (0.16, 1.52)], CPR [26.9 vs. 25.6%, respectively; adjusted OR (95%CI): 0.44 (0.12, 1.67)], and IMPR [17.3 vs. 16.7%, respectively; adjusted β (95%CI) - 5.6% (- 15.0, 3.9)].

CONCLUSION

Our findings suggest that transferring embryos on D2 versus D3 in women with a limited number of 2PN stage zygotes does not affect early pregnancy outcomes. These results indicate that there can be some flexibility in scheduling the day of transfer at the convenience of both the patient and the center.

Efficacy of embryo transfer on day 2 versus day 3 according to maternal age in patients with normal ovarian response

Objective

Delaying embryo transfer (ET) enables us to select among the embryos available for transfer and is associated with positive effects on implantation and pregnancy outcomes. However, the optimal day for ET of human cleavage-stage embryos remains controversial.

Methods

A retrospective study of 3,124 in vitro fertilization/intracytoplasmic sperm injection cycles (2,440 patients) was conducted. We compared the effects of day 2 and 3 ET on rates of implantation and pregnancy outcomes between young maternal age (YMA; <38 years old, n=2,295) and old maternal age (OMA; ≥38 years old, n=829) patient groups.

Results

The YMA and OMA groups did not differ in terms of patient characteristics except for the proportion of unexplained factor infertility, which was significantly greater in the OMA group, and the proportion of arrested embryos, which was significantly greater in the YMA group. However, the biochemical pregnancy, clinical pregnancy, ongoing pregnancy, abortion, and implantation rates per cycle were not significantly different between day 2 and 3 ET in the YMA group or the OMA group.

Conclusion

We suggest that offering patients the opportunity to decide which day would be suitable for ET could be part of a patient-friendly protocol that takes into consideration an infertile woman's circumstances and work schedule by allowing ET to be performed on day 2 instead of the traditional transfer on day 3.

Day three versus day two embryo transfer following in vitro fertilization or intracytoplasmic sperm injection

BACKGROUND

Embryo transfer (ET) was traditionally performed two days after oocyte retrieval; however, developments in culture media have allowed embryos to be maintained in culture for longer periods. Delaying transfer from Day two to Day three would allow for further development of the embryo and might have a positive effect on pregnancy outcomes.

OBJECTIVES

To determine if there are any differences in live birth and pregnancy rates when embryo transfer is performed on day three after oocyte retrieval, compared with day two, in infertile couples undergoing treatment with in vitro fertilisation (IVF), including intracytoplasmic sperm injection (ICSI).

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility Group Specialised Register of Controlled Trials, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid), Embase (Ovid), PsycINFO (Ovid) from the inception of the databases to 26th April 2016. We also searched ClinicalTrials.gov and the WHO portal for ongoing trials plus citation lists of relevant publications, review articles and included studies, as well as abstracts of appropriate scientific meetings.

SELECTION CRITERIA

Randomised controlled trials that compared Day 3 versus Day 2 embryo transfer after oocyte retrieval during an IVF or ICSI treatment cycle in infertile couples.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. We contacted study authors for additional information. The primary outcome measures were live birth rate and ongoing pregnancy rate.

MAIN RESULTS

We included 15 studies. Fourteen studies reported data per woman (2894 women) and one study reported data per cycle (969 cycles). The quality of the evidence using the GRADE approach ranged from moderate quality to very low quality. The main reasons for downgrading evidence were poor methodological reporting, selective reporting, inconsistency and imprecision. Live birth per woman - Overall, there was no evidence of a difference in live birth rate between Day three and Day two embryo transfer (risk ratio (RR) 1.05, 95% confidence interval (CI) 0.89 to 1.23; three studies, n = 1200 women; I2 = 63%; very low quality evidence). The data suggest that if 32% of women who underwent a Day two embryo transfer had a live birth, then between 28% to 39% of women undergoing a Day three embryo transfer would have a live birth. Ongoing pregnancy per woman - There was no evidence of a difference between Day three and Day two embryo transfer for ongoing pregnancy (RR 0.98, 95% CI 0.85 to 1.12; six studies, n = 1740 women; I2 = 52%; very low quality of evidence). The data suggest that if 33% of women undergoing a Day two embryo transfer had an ongoing pregnancy then between 28% to 37% of women undergoing a Day three embryo transfer would have an ongoing pregnancy. Clinical pregnancy per woman - There was no evidence of a difference between Day three and Day two embryo transfer for the chance of a clinical pregnancy (RR 1.08, 95% CI 0.98 to 1.19; 12 studies, n = 2461, I2 = 51%; very low quality evidence). The data suggest that if 39% of women undergoing Day two embryo transfer had a clinical pregnancy, then between 38% to 46% of women undergoing a Day three embryo transfer would have a clinical pregnancy. Multiple pregnancy per woman - There was no evidence of a difference between Day three and Day two embryo transfer for the risk of a multiple pregnancy (RR 1.12, 95% CI 0.86 to 1.44; eight studies, n = 1837; I2 = 0%; moderate quality evidence). The data suggest that if 11% of women undergoing Day two embryo transfer had a multiple pregnancy, then between 9% to 15% of women undergoing a Day three embryo transfer would have a multiple pregnancy. Miscarriage rate per woman - There was no evidence of a difference between Day three and Day two embryo transfer for the risk of miscarriage (RR 1.16, 95% CI 0.84 to 1.60; nine studies, n = 2153 women, I2 = 26%; moderate quality evidence). The data suggest that if 6% of women undergoing Day two embryo transfer had a miscarriage, then between 5% to 10% of women undergoing a Day three embryo transfer would have a miscarriage. Ectopic pregnancy rate per woman - There was no evidence of a difference between Day three and Day two embryo transfer for the risk of ectopic pregnancy (RR 0.99, 95% CI 0.29 to 3.40; six studies, n = 1531 women, I2 = 0%; low quality evidence). The data suggest that if 0.7% of women undergoing Day two embryo transfer have an ectopic pregnancy, then between 0.2% to 2% of women undergoing Day three embryo transfer would have an ectopic pregnancy.Subgroup analysis for pregnancy outcomes did not identify any differential effect between IVF and ICSI.None of the included studies prespecified complication rate (e.g. OHSS), fetal abnormality or women's evaluation of the procedure as outcomes in their studies.

AUTHORS' CONCLUSIONS

Twelve of 15 studies contributed data that could be included in meta-analyses. The quality of the evidence ranged from moderate to very low. Only three of the 15 studies reported data for live birth, although the data for ongoing pregnancy and clinical pregnancy are consistent with the live birth data, suggesting no difference between Day three and Day two embryo transfer for these outcomes. There was no evidence of a difference identified between Day three and Day two embryo transfer for multiple pregnancy, miscarriage or ectopic pregnancy per woman randomised. No data were reported for complication rate, fetal abnormality or woman's evaluation of the procedure. The current evidence has not identified any evidence of differences in pregnancy outcomes between Day two and Day three embryo transfers. Any further studies comparing these timings of embryo transfer are unlikely to alter the findings and we suggest that this review no longer be updated.

Is the presence of a non-cleaved embryo on day 3 associated with poorer quality of the remaining embryos in the cohort?

PURPOSE

Morphological evaluation is currently considered the single most important predictive measure for assessing embryo quality. The aim of this study was to investigate whether cycles with at least one non-cleaved embryo (i.e., a 1-cell embryo on day 3) have different outcomes compared with cycles in which all embryos had cleaved by day 3.

METHODS

All autologous IVF/ICSI cycles with a fresh day 3 transfer and without using a gestational carrier performed at our center between 1/1/2010 and 12/31/2011 were analyzed retrospectively. Those cycles with at least one non-cleaved embryo on day 3 were compared with all other autologous cycles that had 100% cleaved embryos performed during the study period.

RESULTS

Eight hundred and forty two cycles were included. Of them, 144 cycles comprised the non-cleaved group, and 698 cycles comprised the cleaved group. Cycles in the non-cleaved group had more oocytes retrieved (15.4 ± 7.1 vs. 12.5 ± 7.1, p < 0.001), more zygotes obtained (10.0 ± 5.3 vs. 7.9 ± 5.2, p = <0.001), but the embryos exhibited lower cleavage rates and higher rates of fragmentation and asymmetry compared with controls (p < 0.001). However, spontaneous abortion rates, ectopic pregnancies rates as well as delivery rates were similar between the two groups.

CONCLUSIONS

Our results show that the presence of a non-cleaved embryo on day 3 is associated with a more exuberant response to controlled ovarian stimulation as reflected by more oocytes retrieved. Despite the significant decrease in quality of the whole cohort in the non-cleaved group, implantation, delivery rates and number of embryos frozen were not adversely affected by the presence of a non-cleaved embryo.

Embryo culture and selection: morphological criteria

In this chapter, we have outlined the various morphological criteria for selection of the best embryo at each important milestone encountered in the progress from the oocyte to the blastocyst. As Gerris et al. stated, a combination of one, two, or even three selection points should lead to a more accurate selection of the best embryo, as no one criterion is better than the other. An embryo that fails to meet the entire set of selection criteria must be avoided as culture cannot correct an impaired embryo.

Evaluation of embryo transfer time (day 2 vs day 3) after imposed single embryo transfer legislation: when to transfer?

To determine whether the timing of embryo transfer (day 2 or day 3) affects pregnancy outcome in IVF patients, receiving single or double embryo transfer, 380 patients were included in this retrospective study. All patients underwent GnRH antagonist protocol. When stratified by number of transferred embryos, single embryo transfer (SET) patients undergoing a day 2 embryo transfer (ET) had similar biochemical pregnancy (25% vs 20.4%; p > 0.05) and clinical pregnancy (16.6% vs 14.6%; p > 0.05) rates to SET patients that were undergoing a day 3 ET. A similar observation was again noted in double embryo transfer (DET) patients undergoing a day 2 ET, with similar biochemical pregnancy (35% vs 29.8%; p > 0.05) and clinical pregnancy (25% vs 15.5%; p > 0.05) rates to DET patients undergoing a day 3 ET. Women, despite age, number of transferred embryos and ET timing, have similar reproductive outcomes. Shortening or lengthening the duration of in vitro culture provides no obvious benefit.

Morphological systems of human embryo assessment and clinical evidence

Success rates with IVF have improved remarkably since the procedure was first established for clinical use with the first successful birth in 1978. The main goals today are to perform single-embryo transfer in order to prevent multiple pregnancies and achieve higher overall pregnancy rates. However, the ability to identify the most viable embryo in a cohort remains a challenge despite the numerous scoring systems currently in use. Clinicians still depend on developmental rate and morphological assessment using light microscopy as the first-line approach for embryo selection. Active research in the field involves developing non-invasive methods for scoring embryos and ranking them according to their ability to implant and give rise to a healthy birth. Current attention is particularly being focused on time-lapse evaluation. Available data from preliminary studies indicate that these systems are safe;prospective data now need to be collected to determine whether these methods do improve implantation rates. This review gives brief consideration to the use of morphological evaluations in assisted reproduction treatment, discusses the types of embryo scoring,digital imaging and biometric approaches currently in use and comments on future developments for embryo evaluation.

Embryo Culture Media, Culture Techniques and Embryo Selection: A Tribute to Wesley Kingston Whitten

This review article gives a brief history of the classical experiments that led to the development of the embryo culture medium and in vitro embryo culture. It proposes that, in view of the outstanding and significant pioneering contributions of Wesley Kingston Whitten to the development of embryo culture medium, he be considered the “Father of Embryo Culture Medium”. Furthermore, it describes the nutritional requirements of early embryos and how these requirements with specific references to carbohydrates, amino acids, phosphates, growth factors, etc, have been utilized to formulate increasingly more complex embryo culture media. This has led to the development of progressively more efficacious embryo culture media including the formulation of completely defined and synthetic protein-free embryo culture medium. The review also describes physical factors, growth factors, insemination methods for the fertilization of oocytes and culture methods affecting embryo growth, development, metabolism, oxygen embryotoxicity and survival. In procedural terms, the review also summarizes the evolution of embryo culture techniques from tube culture to, microdrop culture under oil to co-culture to ultra microdrop culture techniques. It includes techniques of in vitro maturation and for the selection of potentially viable embryos of various developmental stages.

Comparison of day 2 tubal embryo transfer with day 3 embryo transfer into the uterus of intracytoplasmic sperm injection derived human embryos

OBJECTIVE

To compare the results of embryo transfer into the uterus (ET) performed on day 3 vs. tubal embryo transfer (TET) on day 2 in couples diagnosed with male factor infertility.

MATERIALS AND METHODS

We collected data from 34 and 110 patients who underwent intracytoplasmic sperm injection (ICSI) followed by either TET on day 2 or ET on day 3 (January 2001-June 2005), respectively. All couples were diagnosed with male factor infertility; there were no tubal or uterine factors, diminished ovarian reserve, pelvic adhesions, history of polycystic ovary syndrome or previous ovarian surgery.

RESULTS

The clinical pregnancy rates of day 2 TET and day 3 ET following ICSI were 64.71% and 57.27% (p > 0.05), respectively. The corresponding implantation rates were 35.47% and 29.58% (p > 0.05), respectively.

CONCLUSION

The implantation and clinical pregnancy rates of ET on the 3rd day following ICSI were similar to the rates obtained with TET 2 days after ICSI. Therefore, ET performed 3 days after ICSI should be the first choice for couples with male factor infertility, while day 2 TET remains a good alternative, especially for women with normal tubal function and known difficulties of transcervical ET.

Early compaction on day 3 may be associated with increased implantation potential

OBJECTIVE

To determine whether day 3 embryos exhibiting early compaction have an improved implantation potential compared to embryos without compaction.

DESIGN

A retrospective cohort study.

SETTING

Hospital-based academic medical center.

PATIENT(S)

Women <38 years of age undergoing IVF cycles between November 2001 and December 2004 having a day 3 transfer of one or two embryos with >8 cells.

INTERVENTION(S)

Standard IVF protocol.

MAIN OUTCOME MEASURE(S)

Compaction grading and implantation rates of 1,047 embryos as related to fragmentation of >or= 8-cell embryos in patients with either 0% or 100% implantation.

RESULT(S)

Compaction grading was strongly associated with implantation potential; however, the direction of this effect depended on the degree of fragmentation. In embryos with <10% fragmentation, implantation rates increased with the degree of compaction (grade 1, 25%; grade 2, 33%; and grade 3, 47%); in embryos with >or=10% fragmentation, the effect was reversed (grade 1, 38%; grade 2, 20%; and grade 3, 9%).

CONCLUSION(S)

Assessing the degree of compaction can be a valuable addition to traditional morphologic assessment in identifying optimal embryos for transfer on day 3.

Day 3 compared with day 2 cryopreservation does not affect embryo survival but improves the outcome of frozen-thawed embryo transfers

A retrospective study was performed to determine the differences in embryo survival and frozen-thawed embryo transfers outcome between cryopreservation performed on day 3 versus day 2. We conclude that freezing supernumerary embryos on day 3 provides similar thawing survival parameters, better implantation, pregnancy, and live-birth rates compared with day 2 cryopreservation.

Day 2 transfer improves pregnancy outcome in in vitro fertilization cycles with few available embryos

OBJECTIVE

Delaying ET to day 3 to optimize embryo selection is well accepted. However, in cases where there are not enough embryos to perform selection, it is not clear whether there is a difference in clinical outcomes with the day of ET.

DESIGN

Cohort study.

SETTING

Academic medical center.

PATIENT(S)

Two hundred forty-two fresh IVF/intracytoplasmic sperm injection (ICSI) cycles from 2002-2004, where all generated embryos were transferred irrespective of quality because of an extremely low number of available embryos.

INTERVENTION(S)

In time period 1, ET was on day 3. In time period 2, ET was on day 2.

MAIN OUTCOME MEASURE(S)

Patient response to stimulation was analyzed along with pregnancy outcome and implantation rate.

RESULT(S)

Miscarriage rates were decreased, and ongoing pregnancy rates were increased with a day 2 ET in patients <40 years of age.

CONCLUSION(S)

In women <40 years of age, the day of transfer is a significant predictor of clinical outcome in cases in which a low number of embryos are available for transfer. The evidence suggests that limiting embryo culture to only 2 days reduces the incidence of miscarriage and increases ongoing pregnancy rates.

A randomized control comparison study of culture media (HTF versus P1) for human in vitro fertilization

OBJECTIVE

It is now widely accepted that increasing the number of replacement embryos (>3 embryos per embryo transfer [ET]) is associated with an increased risk of multiple pregnancies. While embryo reduction is often proposed when there is a high risk of multiple pregnancies, it is a difficult decision for the couple. For this reason, different studies have focused on single embryo transfer, more precisely blastocyst transfer. The aim of the study is to confirm that phosphate-free culture media can be used to generate greater quality embryos.

METHODS AND RESULTS

We carried out a study to compare the efficacy of human tubal fluid (HTF) versus preimplantation stage one (P1) as culture media for assisted reproductive therapy (ART). In 109 nonselected patients, we obtained an embryo fertilization rate with HTF and P1 culture media of 58.6 and 62.5% (P = 0.003), respectively. After 48 and 72 h, the morphology was similar for both P1 and HTF embryos in most patients. However, in the same patients, when HTF embryo quality was low (15.4%), P1 embryo quality was significantly higher 68.7% (P = 0.002). Some embryos were transferred at 48 h and some at 72 h after retrieval, in a randomized manner. We transferred a maximum of up to three embryos per ET. The implantation rate was significantly different; at 48 h, it was 6.8 and 12.2% for HTF and P1, respectively (P = 0.02). The pregnancy rate was 17.1% for HTF embryos and 23.7% for P1 embryos (P = 0.02).

CONCLUSIONS

Therefore, we observed a significant difference between P1 and HTF in the fertilization rate, in embryo quality, in implantation rate and in pregnancy rate. But the most important difference between this study and others is that every patient was the control of herself, so we eliminated every variable.

Randomized study comparing day 2 versus day 3 elective transfer of two good-quality embryos

Objective:  The number of embryos transferred is very important to avoid multiple pregnancies without compromising pregnancy rates in in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI)-embryo transfer (ET). We established criteria for the elective transfer of two embryos (age <40, first treatment cycle, good-quality embryos ≥3) to avoid high-order multiple pregnancies, and reported their usefulness. In the current study, we compared the clinical outcome of day 2 versus day 3 elective transfer of two good-quality embryos, in order to investigate the day of preferential transfer. Methods:  A total of 228 cycles were treated with IVF/ICSI-ET from August 1999 to August 2002. From this total, 114 patients who were less than 40 years old and also had a first treatment cycle were enrolled in the present study (50.0%). The elective transfer of two good-quality embryos was carried out in 36 cycles (31.6%). Patients were randomized for transfer on either day 2 or day 3 after oocyte retrieval. Results:  The pregnancy rate of women who received two good-quality embryos was 44.4% (16 out of 36). The multiple pregnancy rate was 12.5% (two out of 16) and all pregnancies outcomes were twins. There were no significant differences between day 2 and day 3 ET for the following criteria: the number of cycles (24, 12); age (32.8 ± 3.4 years, 32.5 ± 2.7 years); number of oocytes retrieved (10.0 ± 3.3, 9.0 ± 6.0); number of embryos developed (7.6 ± 3.5, 6.9 ± 3.7); and number of good-quality embryos cryopreserved (3.5 ± 2.7, 3.6 ± 2.1). Higher pregnancy and implantation rates were obtained in day 3 ET than day 2 ET (37.5 and 20.8% in day 2 ET vs 58.3 and 33.3% in day 3 ET); however, there were no significant differences. Conclusion:  Day 3 ET appears to be preferable to achieve more viable embryos than day 2 ET. (Reprod Med Biol 2004; 3: 99-104).

Day three versus day two embryo transfer following in vitro fertilization or intracytoplasmic sperm injection

BACKGROUND

Embryo transfer (ET) was traditionally performed two days after oocyte retrieval; however, developments in culture media have allowed embryos to be maintained in culture for longer periods. Delaying transfer from day two to day three would allow for further development of the embryo and might have a positive effect on pregnancy outcomes.

OBJECTIVES

To determine if there is any difference in live birth and pregnancy rates when ET is performed on day three, compared with day two, in infertile couples undergoing treatment with in vitro fertilization (IVF), including intracytoplasmic sperm injection (ICSI).

SEARCH STRATEGY

We searched the Cochrane Menstrual Disorders & Subfertility Group trials register (17th December 2003), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 1, 2003), MEDLINE (1966 to 2003), EMBASE (1980 to 2003) and Biological Abstracts Databases (1980 to 2003), the National Research Register (NRR), the Medical Research Council's Clinical Trials Register, the NHS Centre for Reviews and Dissemination, citation lists of relevant publications, review articles and included studies, as well as abstracts of appropriate scientific meetings.

SELECTION CRITERIA

Randomized controlled trials that compared day three versus day two embryo transfer after oocyte retrieval during an IVF or ICSI treatment cycle in subfertile couples.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for additional information. The primary outcome measures were live birth rate and ongoing pregnancy rate.

MAIN RESULTS

Ten studies involving 2027 women were included, but only three studies reported live birth and four reported ongoing pregnancy rates. The pooled odds ratios (day three compared to day two) were 1.07, 95% CI 0.84 to 1.37 for live birth and 1.05, 95% CI 0.83 to 1.32 for ongoing pregnancy. From ten studies, the pooled odds ratio for clinical pregnancy was 1.26, 95% CI 1.06 to 1.51. Sub-group analysis revealed that this advantage occurred in those undergoing ICSI cycles. A higher miscarriage rate with day 3 ET in ICSI cycles works to negate the increased clinical pregnancy rate, in agreement with the finding of no significant difference between treatments in live birth rate.

REVIEWERS' CONCLUSIONS

Although an increase in clinical pregnancy rate with day three embryo transfer was demonstrated, at present there is not sufficient good quality evidence to suggest an improvement in live birth when embryo transfer is delayed from day two to day three.

Implantation Rates after Two, Three, or Five Days of Embryo Culture

Extended embryo culture together with amelioration of embryo selection methods and embryo culture conditions have allowed a substantial increase on both pregnancy and implantation rates. However, uterine embryo transfers are still performed after 2 to 6 days of egg retrieval. In this paper, we show the results of two studies, one prospective study comparing IVF outcome of day 2 and day 3 embryo transfers, and a retrospective study looking at blastocyst transfers versus day 3 embryo transfers in our egg donation program. Also, we test the predictive value of the presence of three or more seven cell-stage embryos on day 3 of development on blastocyst formation and pregnancy rates. No significant differences were found between day 2 and day 3 embryo transfers in terms of pregnancy, ongoing pregnancy, and implantation rates, as well as in multiple and in high order pregnancy. In general, day 6 embryo transfers resulted in significantly higher ongoing pregnancy and implantation rates compared with day 3 embryo transfers (41.1 per cent and 23.6 per cent versus 50.1 per cent and 38.1 per cent, respectively). No differences were found in terms of multiple gestations despite transferring significantly more embryos on day 3 compared with day 6 transfers. When less than three 7-cell embryos were present in the embryo cohort, day 6 embryo transfers did not improve the rates of ongoing pregnancy with regards to day 3 embryo transfer, although significant high implantation rates were obtained on the group of blastocyst transfer. The presence of three or more 7 cell-stage embryos improved significantly both ongoing pregnancy and rates on blastocyst transfers compared to day 3 embryo transfers (65.6 per cent versus 50.6 per cent and 37.4 per cent vs 24.7 per cent, respectively). In conclusion, at least in egg donation, day 3 embryo transfers do not improve either pregnancy or implantation rates when compared to day 2 transfers. Generally speaking blastocyst transfers give significantly higher chance of pregnancy and implantation rates per cycle and per transfer than early cleavage stage transfers. However, the absence of a good embryo cohort, that is having less than three 7 cell-stage embryos on day 3, blastocyst transfers will improve implantation rates but not ongoing pregnancy rates.

Pregnancy rate is not improved by delaying embryo transfer from days 2 to 3

OBJECTIVE

To compare the outcome of assisted reproduction in day 2 versus day three embryo transfer.

DESIGN

Prospective study.

PARTICIPANTS

A total of 927 consecutive embryo transfers for IVF and ICSI cycles including 626 embryo transfers on day 2 and 301 on day 3.

INTERVENTION

IVF and ICSI.

OUTCOME MEASURE

Clinical pregnancy rate.

RESULTS

There is no significant difference in the pregnancy rate between ET on day 2 (50.9%) and ET on day 3 (50.5%).

CONCLUSION

Embryo transfer could be done on days 2 or 3 according to the convenience of the patient and the medical team.

CONDENSATION

Embryo transfer could be done on days 2 or 3 according to the convenience of the medical team with similar results.

A prospective randomized multicenter study to evaluate the best day for embryo transfer: does the outcome justify prolonged embryo culture?

PURPOSE

This study aimed to evaluate the best day for embryo transfer in a prospective unrestricted randomized multicenter trial.

METHODS

Data were collected on a preformed Excel-sheet which contained random numbers from 1 to 5 for each subsequent patient as a preprogrammed day for embryo transfer. Information was requested on patient's age, indication for sterility treatment, stimulation protocol used, numbers of oocytes retrieved, fertilized oocytes, cryopreserved embryos, and cell stage of embryos transferred.

RESULTS

A total of 329 embryo transfers were performed, resulting in 106 clinical pregnancies (32.2%). Pregnancy rates achieved were 20.0% on day 1, 30.4% on days 2 and 3, and 50.0% on days 4 and 5 (p = 0.03).

CONCLUSIONS

Within the scope of the present randomized multicenter trial, embryo transfers performed on days 4 and 5 enhanced the pregnancy rate significantly, compared to those of days 1, 2, and 3.

Improvement in early human embryo development using new formulation sequential stage-specific culture media

OBJECTIVE

To determine whether altering selected components of sequential culture media can improve early development variables of human embryos.

DESIGN

Prospective, randomized, sibling oocyte split trial.

SETTING

Private ART center.

PATIENT(S)

Two hundred eight undergoing treatment with in vitro fertilization or microinjection.

INTERVENTION(S)

Oocytes from each patient were randomly allocated to fertilization and cleavage media of a control and a trial culture medium formulation.

MAIN OUTCOME MEASURE(S)

Rates of fertilization, cleavage, and uncontrolled division; average embryo morphology score; blastomeres per embryo; embryo score parameter (number of blastomeres x embryo morphology grade); and embryo utilization. The trial media resulted in a higher fertilization rate, higher cleavage rate, lower rate of uncontrolled division, higher number of blastomeres per embryo, higher average embryo morphology score, a higher embryo score parameter, and higher embryo utilization rate compared to the control media. All differences were statistically significant.

CONCLUSION(S)

Improved sequential stage-specific culture media can reduce the occurrence of severe human embryo fragmentation and improve developmental variables in early IVF- and ICSI-generated embryos.

Blastocyst culture in human IVF: the final destination or a stop along the way?

In the field of human IVF, culturing embryos to the blastocyst stage has gained popularity within the past few years. The impetus to transfer blastocysts has been spurred by several factors: 1) the desire to improve implantation rates in infertility patients, 2) a desire to reduce the multiple pregnancy rate by transferring fewer embryos, 3) the desire to perform pre-implantation genetic diagnosis, and 4) the advent of sequential media. Although culturing human embryos to the Hastocyst stage has improved implantation rates and reduced the incidence of multiple pregnancies in some patient populations, it has not worked for all populations of infertility patients. Factors that may affect the ability of a human embryo to reach the blastocyst stage include the patient's age, cohort of ova retrieved, the use of intracytoplasmic sperm injection of blastomere biopsy, culture conditions, or intrinsic factors within the embryo itself. Culture of human embryos to the blastocyst stage can be an effective method for improving implantation rates and reducing the high order multiple pregnancy rates seen in human IVF clinics when more than three embryos are transferred.

A novel system for in vitro maturation of human oocytes

OBJECTIVE

To compare in vitro maturation of cumulus-free oocytes in glucose-free medium (P1) and standard medium (TC199).

DESIGN

Prospective, cohort study.

SETTING

Assisted reproductive technology program.

PATIENT(S)

One hundred eight patients undergoing ICSI.

INTERVENTION(S)

Germinal vesicle-stage or metaphase I--stage oocytes were allocated to culture with P1 or TC199. Metaphase II oocytes were fixed for immunofluorescence analysis or fluorescence in situ hybridization at 24 or 48 hours (or both). Media were compared by performing conditional logistic regression analysis that controlled for egg-specific factors.

MAIN OUTCOME MEASURE(S)

Proportion of mature oocytes and appearance of normal spindle-chromosome cytoarchitecture.

RESULT(S)

At 24 hours, more P1 oocytes than TC199 oocytes reached metaphase II (59.7% vs. 44.9%). At 48 hours, 71.7% of P1 oocytes and 61.0% of TC199 oocytes reached metaphase II, but this difference was not significant. Metaphase II oocytes in P1 were 34.3% more likely than those in TC199 to have a bipolar spindle with aligned chromosomes. Compared with oocytes at the germinal vesicle stage at 0 hour, those at metaphase I at 0 hour were more likely to progress to metaphase II (72.6% vs. 46.1% at 24 hours; 84.1% vs. 60.6% at 48 hours).

CONCLUSION(S)

P1 is superior to TC199 for in vitro maturation of granulosa-free human oocytes.

A prospective, randomized study comparing day 2 and day 3 embryo transfer in human IVF

It is believed that delayed transfer of embryos after IVF allows for a better selection of good quality embryos. Hence, the number of embryos and all other prognostic factors being equal, transfer of day 3 embryos should be associated with higher implantation and pregnancy rates than transfer of day 2 embryos. To investigate this hypothesis, a prospective randomized study was carried out to compare implantation and pregnancy rates between day 2 and day 3 transfers. The relationship between the embryo quality score of day 2 and day 3 embryos and their respective implantation rates was also analysed. In a 2 year period all patients undergoing infertility treatment and in whom at least seven normally fertilized oocytes were obtained were included in the study. A minimization procedure was performed taking into account the patient's age and the method of fertilization (IVF or intracytoplasmic sperm injection). By using a uniform policy of embryo transfer, the number of embryos transferred was similar in both groups. The outcome parameters were embryo quality, implantation and pregnancy rates. No difference was observed in implantation and pregnancy rates between transfers on day 2 versus day 3 (23.8 versus 23.8% and 47.9 versus 46.8% respectively). The incidence of embryos of moderate to poor quality was higher in embryos cultured for 3 days compared with those cultured for 2 days. It is concluded that the outcomes of embryo transfer in terms of implantation and pregnancy rates are comparable for day 2 and day 3 embryos, although the overall embryo quality score decreases when embryos are kept in culture till day 3.

The number of eight-cell embryos is a key determinant for selecting day 3 or day 5 transfer

OBJECTIVE

To select patients for day 3 vs. day 5 embryo transfer.

DESIGN

Retrospective analysis of assisted reproduction technology (ART) cycles comparing outcomes of day 3 and day 5 transfers.

SETTING

ART program of Brigham and Women's Hospital.

PATIENT(S)

Patients with day 3 or day 5 embryo transfers (n = 221 and 141, respectively).

INTERVENTION(S)

Cycles with eight or more zygotes were stratified by the number of eight-cell embryos available on day 3 (none, one or two, or three or more).

MAIN OUTCOME MEASURE(S)

Number of blastocysts, implantation rates, ongoing pregnancy rates, and number of fetal heart beats.

RESULT(S)

With no eight-cell embryos on day 3, 0% and 33% pregnancies resulted from day 5 vs. day 3 transfers. With one or two eight-cell embryos on day 3, ongoing and high order multiple rates were not different between day 3 and day 5 transfers. With three or more eight-cell embryos, day 5 transfer resulted in a decrease in multiple gestations but no difference in ongoing pregnancy rates compared with day 3 transfer.

CONCLUSION(S)

With no eight-cell embryos on day 3, a day 3 transfer is warranted. With one or two eight-cell embryos, any benefit of day 5 transfer appears to be equivocal. With three or more eight-cell embryos, day 5 transfer is recommended.

Formulation of a protein-free medium for human assisted reproduction

The optimal concentrations of individual amino acids, antioxidants, vitamins, osmolytes and energy sources were determined using a 1-cell Swiss outbred (SO) and or F(1) [(CBAxC57BL/6J)xSO] mouse assay in Earle's balanced salt solution containing bovine serum albumin. Based on the findings of these experiments, a number of media were formulated. Of these, the medium showing optimal embryo development and a significantly higher blastocyst hatching rate was investigated further. A protein-free medium (ART-7) was formulated and assessed using 1-, 2- and 4-cell SO mouse embryos. The generation of viable human embryos in the ART-7 series of media in micro- and ultra micro-droplet culture under oil with and without cumulus co-culture following intracytoplasmic sperm injection (ICSI) was investigated. The quality of sibling day 2 human embryos generated in the ART-7 media series was statistically comparable to or better than control embryos. The ART-7 medium was not toxic to human spermatozoa. Fertilization by conventional IVF and subsequent embryo development was not affected. A clinical trial of ICSI-derived embryos generated in the protein-free medium, with and without cumulus co-culture, has resulted in clinical pregnancies (10 of 20 transfers) of which two have proceeded to term, and the remaining patients are in various stages of pregnancy.

Clinical outcome of day 2 versus day 3 embryo transfer using serum-free culture media: a prospective randomized study

PURPOSE

The objective was to evaluate whether extending the embryo culture period from 2 to 3 days would yield a more optimal selection of viable embryos, thereby increasing the implantation and live birth rates.

METHODS

Patients undergoing in vitro fertilization with at least one oocyte fertilized were prospectively randomized to 2 or 3 days of embryo culture in serum-free media. On the basis of their morphology and cleavage rate, a maximum of three embryos was selected for transfer.

RESULTS

Embryos transferred on day 2 or day 3 were similar morphologically, however, a higher proportion of retarded embryos was observed on day 3. The implantation rate was 15.8 and 14.3% for day 2 and day 3 transfers, respectively. The increase in live birth rate from 18.5 to 22.6%, possibly suggesting a better embryo selection on day 3, was not statistically significant.

CONCLUSIONS

Extending the embryo culture period from 2 to 3 days had no effect on implantation and live birth rates.

Elective transfer of one embryo results in an acceptable pregnancy rate and eliminates the risk of multiple birth

To avoid multiple pregnancies without compromising pregnancy rates (PR) is a challenge in assisted reproduction. We have compared pregnancy results among 74 elective one-embryo transfers (group 2) and 94 transfers where only one embryo was available (group 1). All the fresh embryo cycles during 1997 in two clinics in Helsinki were analysed, and cumulative PR among these couples after frozen-thawed embryo transfers up to June 1998 were counted. In group 2, where at least two embryos were available for transfer, and only one was transferred on day 2 or 3, the PR per embryo transfer was 29.7%. In group 1, the PR per embryo transfer was 20.2%. In group 2, the cumulative PR after frozen-thawed embryo transfers was 47.3% per oocyte retrieval. Over the same time, 742 two-embryo transfers were carried out. The PR per embryo transfer was 29.4% in these subjects, but 23.9% of these pregnancies were twins. The implantation rates, as well as the PR, were highest when the embryos were at the four- to five-cell stage on day 2 (35.8 versus 9.7% compared with the two- to three-cell stage, P < 0.001) or at the six- to eight-cell stage on day 3 (45.5%). The PR per embryo transfer was higher when a grade 1 or 2 embryo was transferred compared with a grade three embryo (34. 0 and 26.7% versus 8.8% respectively, P < 0.05). In women 35 years or younger, the PR per elective one-embryo transfer was 32.8%. The corresponding figure in women older than 35 years was 18.8%. On the basis of these results, elective one-embryo transfer can be highly recommended, at least in subjects who are younger than 35 years of age, and who have grade one or grade two embryos available for transfer.

Glucose-free medium in human in vitro fertilization and embryo transfer: a large-scale, prospective, randomized clinical trial

OBJECTIVE

To determine whether excluding glucose from the culture medium used in a clinical IVF program improves human embryo quality and pregnancy rates.

DESIGN

Randomized controlled trial.

SETTING

Clinical assisted conception laboratory in a large teaching hospital.

PATIENT(S)

Seven hundred forty-one patients undergoing IVF-ET.

INTERVENTION(S)

Embryos were cultured from the pronucleate stage to ET in medium with glucose for patients in the control group and without glucose for patients in the trial group.

MAIN OUTCOME MEASURE(S)

Comparison of embryo quality and pregnancy rates between the two groups.

RESULT(S)

Embryo quality was enhanced with the use of glucose-free medium but pregnancy rates were similar.

CONCLUSION(S)

Although pregnancy rates remained similar in the two groups, a reduction in the glucose concentration of the medium used for embryo culture from the pronucleate stage to ET on day 2 or 3 is prudent.

A study failing to determine significant benefits from assisted hatching: patients selected for advanced age, zonal thickness of embryos, and previous failed attempts

PURPOSE

Pregnancy and implantation rates after mechanical assisted hatching (AH) in patients aged > or = 38 years, with embryos > or = 15 microns in zonal thickness and two or more failed attempts, were assessed at two infertility centers using fresh and frozen embryo transfer (FET) cycles.

METHODS

AH was performed on 3-day-old embryos. Spare embryos cryopreserved at the two-pronucleus stage were subjected to AH after 2 days of culture and transferred to artificially prepared uteri.

RESULTS

In fresh cycles, no significant differences in pregnancy rates (clinical and ongoing) and implantation rates were observed between the AH and the controls for all three selected patient groups (Centers 1 and 2). In FET cycles, AH tended to give poor results for > or = 38 year olds (clinical pregnancy rates of 0 and 5.0% with AH vs 13.3 and 16.7% for controls at Centers 1 and 2, respectively). With AH, embryos with thick zonae implanted to the same extent as those in the control group and achieved pregnancies for patients with multiple failures (four to six attempts for some) in both fresh and FET cycles.

CONCLUSIONS

AH failed to show significant benefits in all three patient groups. A larger study group may confirm the effects of AH on frozen/thawed embryos and outcomes for multiple failure cases.

Culture and transfer of human blastocysts

The transfer of the human embryo at the blastocyst stage during an in-vitro fertilization procedure is a way of increasing implantation rates. This, in turn, means that significantly fewer embryos are required to be transferred in order to establish a successful pregnancy. The result of this is that high order multiple gestations are eliminated, while maintaining high pregnancy rates, in in-vitro fertilization.

Preliminary clinical experience with human blastocyst development in vitro without co-culture

This preliminary analysis was designed to quantify blastocyst development of supernumerary embryos without the use of feeder cells, conditioned medium or whole serum. Embryos derived from in-vitro fertilization (IVF) that were not transferred or cryopreserved were included in this study. Ova were harvested for IVF after a standard ovarian stimulation with gonadotrophin-releasing hormone agonist/ human menopausal gonadotrophin (GnRHa/HMG) or follicle-stimulating hormone (FSH). Ova were collected and culture in 150 microliters droplets of P1 medium under mineral oil, in groups at 37 degrees C under 5% CO2, 5% O2, 90% N2 (group A) or under 5% CO2 in air (group B) environment. Embryo transfer was performed 72 h post-harvest. Viable embryos not transferred or cryopreserved were placed in blastocyst medium and cultured for an additional 48 h in 5% CO2 in air. Embryos that exhibited an expanded blastocoelic cavity and well-defined inner cell mass at 120 h were counted. Of 838 supernumerary embryos cultured, 448 (53.5%) reached the expanded blastocyst stage by 120 h of culture. Patients were given the option of cryopreservation at that time. The embryos were cryopreserved using a standard protocol with serial addition of glycerol. Embryos reaching the blastocyst stage after more than 120 h of culture were not included. There was no difference in the proportions of blastocyst development between group A, 217/410 (53.5%) and group B, 231/428 (54%). To date, 16 patients have each had up to three thawed blastocysts transferred, out of whom seven became pregnant. This report demonstrates that a simple system of sequential culture generated acceptable, viable blastocyst development (54%) with supernumerary embryos, without the use of feeder cells, conditioned medium or whole serum. Recognizing the differential metabolic requirements of early and late cleavage stage embryos has enabled the application of a glucose/phosphate-free simple culture medium (P1) for up to 72 h of culture and a complex, glucose-containing medium (blastocyst medium) for subsequent blastocyst development.

Oolemma rupture inside the intracytoplasmic sperm injection needle significantly improves the fertilization rate and reduces oocyte damage

OBJECTIVE

To compare the effect on fertilization, oocyte damage, embryo freezing, and pregnancy rates of two different techniques for rupturing the oolemma during intracytoplasmic sperm injection (ICSI).

DESIGN

Retrospective study.

SETTING

Fertility Center, Alliant Health System Hospital.

PATIENT(S)

Seventy-nine consecutive IVF-ICSI cases.

INTERVENTION(S)

Patients in group I had ICSI performed by pushing the needle into the oocyte until the oolemma was observed to break outside the needle. In group II the oolemma was aspirated into the needle until it ruptured inside the needle.

MAIN OUTCOME MEASURE(S)

In group II ICSI resulted in significantly higher fertilization and lower oocyte damage rates (66% and 13%) than in group 1 (39% and 29%). There were no statistically significant differences in embryo cleavage rates or pregnancy rates per retrieval between the two groups. A greater number of cases had embryos cryopreserved in group II than in group I.

RESULT(S)

Rupturing the oolemma by aspirating it into the ICSI needle (group II) improved laboratory outcomes compared with the more traditional technique of breaking this membrane by the stabbing action of the needle (group I). This modification of the ICSI technique also increased the number of patients with cryopreserved embryos and therefore could increase the pregnancy rate per patient.

CONCLUSION(S)

The site and technique used to rupture the oolemma during ICSI has a significant effect on the fertilization and damage rates.