The Effect of Post-Thaw Culture on Frozen Embryos Transfer Outcomes

INTRUDUCTION:
The use of frozen embryos is an essential component in assisted reproductive technology. Post thaw culture may contribute to the selection of embryos with evidently continues blastomer proliferation.

AIM:
To assess the impact of post thawing embryo culture on frozen embryos transfer (FET) outcomes.

MATERIALS AND METHODS:
A retrospective cohort study including 678 FET cycles performed between the years 2004 – 2017 was conducted. Patients above 45 years old were excluded. FET cycles were stratified to: 1) two-day (2d) thawed embryos cultured to three-day (3d) versus 3d thawed and transferred and 2) 2d or 3d thawed embryos cultured to blastocyst versus blastocyst thawed and transferred. A p value of <0.05, was considered statistically significant.

RESULTS:
Maternal age, BMI, smoking and basal FSH, of the 2d and 3d cultured embryo group (n=110) and the 3d non-cultured embryo group (n=189) were comparable. Endometrium preparation protocols and the achieved endometrial thickness did not differ between groups. Pregnancy rate, implantation rate, clinical pregnancy, live birth rate, abortions, multiple pregnancies, perinatal outcomes and birth weight were comparable.
Comparing the 2d and 3d cultured to blastocyst group (n=41) to blastocyst non-cultured group (n=338), the non-cultured blastocyst group had higher smoking rates and longer follicular length. Endometrial thickness was comparable. The 2d and 3d embryos cultured to blastocyst group had higher multiple pregnancies rate compared to the blastocyst non-cultured group whereas pregnancy rate, implantation rate, live birth rate, abortions, perinatal outcomes and birth weight were comparable.

CONCLUSION:
Post thaw culture has no advantage over non-cultured FET in light of treatment outcomes.