Embryo blastulation and quality between days 5 and 6 of extended embryo culture

PURPOSE

This study aims to know what proportion of culture day 5 pre-blastocyst-stage embryos develop into blastocysts by culture day 6 and what patient and cycle characteristics are associated with delayed blastocyst formation.

METHODS

A retrospective observational cohort analysis was performed including a total of 9886 embryos from 1008 IVF cycles in 835 patients, who underwent treatment between January 1, 2016, and December 31, 2018. Autologous fresh in vitro fertilization (IVF) cycles at a single academic center were included in the analysis. Embryos were group-cultured using single-step culture media. Blastulation was defined as the presence of a new blastocyst. Usable blastulation was defined as the presence of a new good or excellent quality, expanded, hatching, or hatched blastocysts.

RESULTS

The mean blastulation rate between days 5 and 6 of extended embryo culture was 30.9%. The mean percentage of embryos developing into usable blastocyst-stage embryos was 19.8%. The factors associated with blastulation on day 6 included the total number of embryos and the number of pre-blastocysts on day 5, as well as the use of ICSI. Age, the number of total embryos, those remained in culture and pre-blastocysts, as well as the blastulation rate on day 5 were associated with usable blastulation.

CONCLUSION

It is important to know the usable blastocyst development rate between culture days 5 and 6 in order to adequately counsel patients debating whether to proceed with fresh ET on day 5 or forego ET with the expectation that embryos will be biopsied for PGT and/or cryopreserved on culture day 6. Our findings provide evidence to help guide patients in this difficult decision.

Live birth and multiple birth rates in US in vitro fertilization treatment using donor oocytes: a comparison of single-embryo transfer and double-embryo transfer

OBJECTIVE

To compare live birth rates (LBRs) and multiple birth rates (MBRs) between elective single-embryo transfer (eSET) and double-embryo transfer (DET) in donor oocyte in vitro fertilization (IVF) treatments in both a cycle-level and clinic-level analysis.

METHODS

Donor oocyte IVF treatments performed by US IVF clinics reporting to the Centers for Disease Control and Prevention in 2013-2014 were included in the analysis. Primary outcomes included LBR and MBR. Secondary outcomes included gestational age at delivery (GA) and birth weight (BW) of offspring. These outcomes were evaluated on an individual cycle level as well as on the clinic level.

RESULTS

In multivariable models, LBR did not change significantly as clinics utilized eSET more frequently. MBR decreased significantly as utilization of eSET increased, from 39% MBR in clinics that utilized eSET 0-9% of the time to 7% MBR in clinics that used eSET 70% of the time (P < .0001). Mean BW and GA of IVF-conceived offspring both increased as clinics utilized eSET more frequently (2778 to 3185 g [P < .0001] and 37.5 to 38.5 weeks [P = .02] for clinics with the lowest and highest eSET utilization, respectively).

CONCLUSIONS

US IVF clinics utilizing eSET with higher frequencies have clinically comparable LBRs and significantly lower MBRs than clinics with lower-frequency eSET utilization. Mean offspring BW and GA increased with higher eSET utilization, further confirming the improved safety of this practice.