Blastocyst development rate influences singleton gestational age of similarly graded blastocysts after vitrified–warmed single embryo transfer cycles

The effect of the day 3 embryo cell number on the neonatal outcomes of day 5 single blastocyst transfer in frozen embryo transfer cycles

OBJECTIVE

To evaluate the influence of the day 3 embryo cell number on the neonatal outcomes of day 5 single blastocyst transfer in frozen embryo transfer (FET) cycles.

METHODS

This retrospective study analysed a total of 2315 delivery cycles of day 5 single blastocyst transfer in FET cycles, including 489, 761 and 1103 live-born infants segregated according to a day 3 embryo cell number of <8, 8 and >8 cells, respectively. The neonatal outcomes of the three groups were compared.

RESULTS

The day 3 embryo cell number did not significantly affect the incidence of monozygotic twins. The sex ratio increased as the day 3 embryo cell number increased, but the difference was not statistically significant. There were no significant differences in the rates of preterm birth or low birth weight among the three groups. The rates of stillbirths and neonatal deaths were also not significantly different among the three groups. Moreover, the day 3 embryo cell number did not increase the risk of birth defects in newborns.

CONCLUSIONS

The day 3 embryo cell number did not significantly affect neonatal outcomes.

Perinatal outcomes of singletons following double vitrification-warming procedures: a retrospective study using propensity score analysis

BACKGROUND

Although repeated cryopreservation is an occasional occurrence, the effect on perinatal outcomes is unclear. Therefore, the aim of this study was to evaluate the perinatal outcomes of singletons after embryo re-cryopreservation.

METHODS

In this retrospective study, a total of 647 singleton live births after blastocyst freeze-thaw embryo transfer cycles were investigated. They were divided into two groups: vitrified-warmed blastocysts (once-vitrified group) and vitrified-warmed blastocysts derived from thawed cleaved embryos (re-vitrified group). Propensity score matching (PSM) was used to control for potential confounding factors.

RESULTS

A total of 592 infants were included in the once-vitrified group, and 55 infants were included in the re-vitrified group. After PSM, 108 cases were generated for comparison. The median gestational age was 38 weeks for both groups, and the birthweights were comparable (3390.6 ± 601.5 g vs. 3412.8 ± 672.6 g, P > 0.05). The incidence of preterm birth (PTB) (20.4% vs. 16.7%), low birthweight (LBW) (3.7% vs. 7.4%), macrosomia (11.1% vs. 16.7%) and large for gestational age (LGA) (29.6% vs. 22.2%) were not significantly different between the two groups. Logistic regression analysis indicated that double vitrification-warming procedures did not affect the occurrence of PTB (OR, 2.58 [95% CI, 0.77, 8.63]), LBW (OR, 0.83 [95% CI, 0.08, 8.29]), macrosomia (OR, 0.60 [95% CI, 0.13, 2.69]), or LGA (OR, 1.51 [95% CI, 0.53, 4.27]) (P > 0.05, for all).

CONCLUSION

Our findings demonstrate that double vitrification-warming procedures do not increase the risk of adverse neonatal outcomes compared with those of once-vitrified embryos.

Blastocyst quality and perinatal outcomes of frozen-thawed single blastocyst transfer cycles

OBJECTIVE

To investigate the effects of blastocyst quality and morphological grade on the perinatal outcomes in patients undergoing frozen-thawed single blastocyst transfer cycles.

METHODS

This single-center retrospective cohort study included 2648 singleton neonates resulting from frozen-thawed single blastocyst transfers performed between January 2017 and September 2021. Multivariate logistic regression was performed to evaluate perinatal outcomes for their association with blastocyst quality and morphological parameters.

RESULT

Transfer of a good-quality blastocyst in a frozen-thawed cycle was associated with a lower rate of preterm delivery (PTD, adjusted OR =0.7, 95% CI 0.5-0.9; P=0.020) and a higher likelihood of a male neonate (adjusted OR =1.2, 95%CI 1.0-1.5; P=0.048). Compared with grade C inner cell mass (ICM) blastocyst transfer, grade B ICM (adjusted OR =0.5, 95%CI 0.2-0.9; P=0.027) and grade A ICM (adjusted OR =0.6, 95%CI 0.3-1.5; P=0.290) blastocyst transfers were associated with a lower rate of PTD, which was more evident for grade B ICM. After adjusting for confounders, the likelihood of a male neonate (grade B TE, OR =1.2, 95%CI 1.0-1.5, P=0.037; grade A TE OR =1.9, 95%CI 1.3-28, P=0.002) increased with increasing trophectoderm (TE) quality. Compared with expansion stage 4, the likelihood of a male neonate was 1.5 times greater with transfer of a stage 6 blastocyst (OR =1.5, 95%CI 1.0-2.3; P=0.06), and the risk of small for gestational age (SGA) was greater with transfer of a stage 5 blastocyst (adjusted OR =3.5, 95%CI 1.5-8.0; P=0.004). The overall grading of the blastocyst, expansion stage, ICM grade, and TE grade were not associated with length at birth, birthweight, large for gestational age (LGA), or birth defects (all P>0.05).

CONCLUSIONS

In frozen-thawed single blastocyst transfer cycles, transfer of a good-quality blastocyst was associated with a lower rate of PTD and a greater likelihood of a male neonate. Transfer of grade B ICM blastocysts decreased the rate of PTD, and TE quality was positively correlated with the likelihood of a male neonate.