First trimester obstetric outcome of frozen thawed embryo transfer: does the stage of embryo make any difference?

Abstract Background The direction of management and outcome of frozen thawed embryo transfer (FET) is becoming different day by day with the invention of newer technologies and application of it as a treatment modality in modern medicine. It also contributes to around 25% of births because of Assisted Reproductive Technology (ART) procedures worldwide today. Methods A prospective longitudinal study was conducted at ART Center of tertiary care hospital. Couples with infertility planned to undergo FET were included in the study. Following FET, all positive cases were followed up till 14 weeks period of gestation. Data were collected and analyzed with appropriate statistical test using Epitable, 6.04 version, and SPSS, version 18, software. Results During the study period, a total of 470 FET cycles were carried out, and 1108 cryopreserved embryos were subjected to thawing procedure. Overall survival rate of 93.86% was noted. Among various stages of embryos thawed, the lowest survival rate (64.62%) was found in blastocyst group. Biochemical pregnancy rate, clinical pregnancy rate, and ongoing pregnancy rate were also analyzed in different subgroup of transferred embryos. The blastocyst group showed best implantation and clinical pregnancy rate but lowest survival rate among all subgroup of embryos. Conclusion The blastocyst transfer during FET cycle showed best clinical and ongoing pregnancy rate. So if clinical situations were favorable for blastocyst stage transfer, the same should be preferred for FET cycle.