Blastocyst culture and transfer: lessons from an unselected, difficult IVF population

Time associations between U.S. birth rates and add-Ons to IVF practice between 2005-2016

Until 2010, the National Assisted Reproductive Technology Surveillance System (NASS) report, published annually by the Center for Disease Control and Prevention (CDC), demonstrated almost constantly improving live birth rates following fresh non-donor (fnd) in vitro fertilization (IVF) cycles. Almost unnoticed by profession and public, by 2016 they, however, reached lows not seen since 1996-1997. We here attempted to understand underlying causes for this decline. This study used publicly available IVF outcome data, reported by the CDC annually under Congressional mandate, involving over 90% of U.S. IVF centers and over 95% of U.S. IVF cycles. Years 2005, 2010, 2015 and 2016 served as index years, representing respectively, 27,047, 30,425, 21,771 and 19,137 live births in fnd IVF cycles. Concomitantly, the study associated timelines for introduction of new add-ons to IVF practice with changes in outcomes of fnd IVF cycles. Median female age remained at 36.0 years during the study period and center participation was surprisingly stable, thereby confirming reasonable phenotype stability. Main outcome measures were associations of specific IVF practice changes with declines in live IVF birth rates. Time associations were observed with increased utilization of "all-freeze" cycles (embryo banking), mild ovarian stimulation protocols, preimplantation genetic testing for aneuploidy (PGT-A) and increasing utilization of elective single embryo transfer (eSET). Among all add-ons, PGT-A, likely, affected fndIVF most profoundly. Though associations cannot denote causation, they can be hypothesis-generating. Here presented time-associations are compelling, though some of observed pregnancy and live birth loss may have been compensated by increases in frozen-thawed cycles and consequential pregnancies and live births not shown here. Pregnancies in frozen-thawed cycles, however, represent additional treatment cycles, time delays and additional costs. IVF live birth rates not seen since 1996-1997, and a likely continuous downward trend in U.S. IVF outcomes, therefore, mandate a reversal of current outcome trends, whatever ultimately the causes.

Clinical outcome of fresh and vitrified-warmed blastocyst and cleavage-stage embryo transfers in ethnic Chinese ART patients

Objectives

This study sought to evaluate the outcome of fresh and vitrified-warmed cleavage-stage and blastocyst-stage embryo transfers in patients undergoing ART treatment within an ethnic Chinese population.

Study design

We compared the clinical results of embryo transfer on the 3rd (cleavage stage) or 5th (blastocyst stage) day after oocyte retrieval, including clinical pregnancy rates, implantation rates and multiple pregnancy rates.

Results

Our data showed that blastocyst transfer on day 5 did not significantly increase clinical pregnancy rate (41.07% vs 47.08%, p>0.05) and implantation rate (31.8% vs 31.2%, p>0.05) in patients under 35 years of age, in comparison with day 3 cleavage stage embryo transfer. In patients older than 35 years of age, the clinical pregnancy rate after blastocyst transfer was slightly decreased compared with cleavage stage embryo transfer (33.33% vs 42.31%, p>0.05). Unexpectedly, It was found that vitrified-warmed blastocyst transfer resulted in significantly higher clinical pregnancy rate (56.8%) and implantation rate (47%) compared with fresh blastocyst transfer in controlled stimulation cycles (41.07% and 31.8%, respectively). For patients under 35 years of age, the cumulative clinical pregnancy rate combining fresh and vitrified-warmed blastocyst transfer cycles were significantly higher compared to just cleavage-stage embryo transfer (70.1% versus 51.8%, p<0.05). However, the cumulative multiple pregnancy rates showed no significant difference between the two groups.

Conclusions

In an ethnic Chinese patient population, fresh blastocyst transfer does not significantly increase clinical pregnancy rate. However, subsequent vitrified-warmed blastocyst transfer in a non-controlled ovarian hyperstimulation cycle dramatically improves clinical outcomes. Therefore, blastocyst culture in tandem with vitrified-warmed blastocyst transfer is recommended as a favourable and promising protocol in human ART treatment, particularly for ethnic Chinese patients.

Sperm DNA fragmentation index does not correlate with the sperm or embryo aneuploidy rate in recurrent miscarriage or implantation failure patients

BACKGROUND

The aneuploidy rate is higher in poor-quality sperm samples, which also have higher DNA fragmentation index values. The aim of this study was to assess the relationship between sperm DNA fragmentation in samples from infertile men belonging to couples with recurrent miscarriage or implantation failure and the aneuploidy rate in spermatozoa as well as in embryos from patients.

METHODS

This prospective study evaluated DNA damage and the aneuploidy rate in fresh and processed (density gradient centrifugation) ejaculated sperm as well as the aneuploidy rate in biopsied embryos from fertility cycles. Fluorescence in situ hybridization was used for the aneuploidy analysis. Results were compared using linear regression and analysis of variance.

RESULTS

A total of 154 embryos were evaluated from 38 patients undergoing PGD cycles; 35.2% of the embryos were chromosomally normal. Analysis of the same sperm samples showed an increased DNA fragmentation after sperm preparation in 76% of the patients. There was no correlation between DNA fragmentation and the aneuploidy rate in embryos or in fresh or processed sperm samples.

CONCLUSIONS

Sperm DNA fragmentation is not related to chromosomal anomalies in embryos from patients with recurrent miscarriage or implantation failure. However, we cannot rule out the possibility that a relationship between DNA fragmentation and aneuploidy exists for other causes of infertility. Furthermore, the different methods used to evaluate DNA fragmentation may produce different results.

Advantages of the two-step embryo transfer strategy in human IVF/ICSI cycles

The aim of this study was to evaluate the advantages of the two-step embryo transfer (ET) strategy combining a day 2/3 ET with a day 5/6 blastocyst transfer. In an observational comparative study, 400 infertile women were enrolled from two assisted reproductive technology (ART) units according to inclusion criteria: age below 42 years and at least three embryos obtained on day 2 thus allowing an extended in vitro culture. Two groups were defined according to the ET strategy adopted: group 1 had a two-step ET; and group 2 had a day 2/3 ET with (subgroup 2a) or without (subgroup 2b) blastocysts cryopreserved on day 5/6. Live birth rate was significantly higher in group 1 than in subgroups 2a and 2b (36.5% versus 29.4% and 13.4%, respectively; p < 10(-3)). Multiple pregnancy rates were comparable between groups. After adjusting on major prognostic factors, the two-step ET strategy was still associated with a significantly higher live birth rate than the day 2/3 ET (OR = 2.23; 95% CI: 1.32-3.77). The two-step ET provides better live birth rates than the cleavage-stage ET. It does not increase multiple pregnancy rates if the number of embryos transferred is limited. It also prevents cycle loss when embryos fail to develop into blastocysts.