The impact of embryo quality on singleton birthweight in vitrified-thawed single blastocyst transfer cycles

Abstract

STUDY QUESTION Does the quality of a single transferred blastocyst affect singleton birthweight in frozen-embryo transfer (FET) cycles? SUMMARY ANSWER The transfer of a poor-quality blastocyst was associated with lower mean birthweight and gestation-adjusted birthweight (Z-scores) when compared with the transfer of an excellent-quality blastocyst during FET cycles. WHAT IS KNOWN ALREADY Embryo quality is a strong predictor of IVF success rates. However, very few studies have examined the effect of embryo quality on singleton birthweight. STUDY DESIGN, SIZE, DURATION This retrospective study involved singleton live births born to women undergoing frozen-thawed single blastocyst transfers during the period from January 2010 to December 2017 at a tertiary care centre. PARTICIPANTS/MATERIALS, SETTING, METHODS A total of 1207 women who fulfilled the inclusion criteria were included and were grouped into four groups depending on the blastocyst quality: excellent, good, average and poor. The primary outcome measure was singleton birthweight. The Z-score was employed to calculate the birthweight adjusted for gestational age and newborn gender. Multiple linear regression analysis was performed to investigate the relationship between embryo quality and neonatal birthweight after adjustment for some potential confounders. MAIN RESULTS AND THE ROLE OF CHANCE In the primary multivariable model, singletons from the poor-quality blastocyst group weighed 183.5 g less than those from the excellent-quality blastocyst group (95% CI: −295.1 to −71.9 g, P = 0.001) in terms of mean birthweight after accounting for patient characteristics, IVF treatment parameters, the year of treatment and newborn gender. Likewise, poor-quality blastocyst transfer was associated with lower gestation-adjusted Z-scores than the transfer of excellent-quality blastocysts (β = −0.35, 95% CI: −0.59 to −0.12, P = 0.003). LIMITATIONS AND REASONS FOR CAUTION The current study was limited by its retrospective design and the fact that our analysis was restricted to women with singleton births from single blastocyst transfers. Future prospective studies are required to confirm our findings. WIDER IMPLICATIONS OF THE FINDINGS Our findings provide new insight into the relationship between embryo quality and neonatal outcomes by showing that poor-quality blastocyst transfer was associated with a decrease in singleton birthweight. STUDY FUNDING/COMPETING INTEREST(S) This study was supported by the National Key Research and Development Program of China (grant no. 2018YFC1003000), the National Natural Science Foundation of China (grant nos. 81771533, 81571397 and 31770989), and the China Postdoctoral Science Foundation (Grant no. 2018M630456). The authors have no conflicts of interest to declare. TRIAL REGISTRATION NUMBER Not applicable.

Live birth rate and neonatal outcomes of different quantities and qualities of frozen transferred blastocyst in patients requiring whole embryo freezing stratified by age

“…Two previously published studies found that singletons derived from poor-quality embryos were not at a higher risk of adverse neonatal outcomes, and embryo quality was not correlated with pregnancy complications [ 23 , 24 ]. Our results are in line with these studies describing that there was no difference in the birth weight of newborns between groups A and E. However, a recent study suggested that the transfer of a poor-quality blastocyst was associated with lower mean birth weight when compared with the transfer of an excellent-quality blastocyst during FET cycles [ 25 ]. The differences in terms of the study population and degree of embryo development may account for the inconsistent results.…”

Live Birth Rate and Neonatal Outcomes of Different Quantities and Qualities of Frozen Transferred Blastocyst in Patients Requiring Whole Embryo Freezing Stratified by Age

“…Two previously published studies found that singletons derived from poor-quality embryos were not at a higher risk of adverse neonatal outcomes and embryo quality was not correlated with pregnancy complications [23,24]. Our results are in line with these studies describing that there was no difference in the birthweight of newborns between group A and E. But, a recent study suggested the transfer of a poor-quality blastocyst was associated with lower mean birthweight when compared with the transfer of an excellent-quality blastocyst during FET cycles [25]. The differences in terms of the study population and embryo development degree may be account for the inconsistent results.…”

Does Estradiol Orally and Vaginally Administered Together Impact Live Birth and Neonatal Outcome in Artificial Frozen-thawed Embryo Transfer Cycles: A Retrospective Cohort Study

“…We didn't include blastocyst embryo transfer into the whole cohort to mitigate the possibleimpact of prolonged in vitro embryo culture on subsequent newborn birthweight and gestational weeks [43,44]. Only homogenous group of patients who achieved adequate endometrial thickness in their rst FET cycles were included to guarantee the relative good-quality embryo transfer and exclude the recurrent FET failure cases, as poor-quality embryos were put forward to be associated with lower birthweight [45]. The long-term follow up of the cohort allowed to provide important neonatal outcomes.…”