Clinical outcomes after transfer of blastocysts derived from frozen-thawed cleavage embryos: a retrospective propensity-matched cohort study.

PURPOSE: To evaluate the clinical outcomes after fresh transfer of blastocysts cultured from vitrified-thawed cleavage embryos (VTCE) compared with conventional frozen-thawed blastocysts transfer (FBT), or with the usual fresh blastocysts transfer (FRBT).

METHODS

A total of 155 cycles undergoing fresh transfer of VTCE blastocysts, 4904 cycles undergoing FBT, and 1014 cycles undergoing FRBT were retrospectively analyzed from August 2014 to July 2017. Pregnancy, delivery, and neonatal outcomes were compared after propensity score matching.

RESULTS

VTCE blastocysts' transfer resulted in a lower risk of early miscarriage (8.82% versus 19.70%, P < 0.05) and a decreased fetal birth weight (2611.90 ± 618.65 g versus 2931.86 ± 546.52 g, P < 0.01) compared to FBT. No significant difference was found regarding live birth rate, gestational age, and cesarean section. Correspondingly, VTCE blastocysts' transfer led to significantly compromised pregnancy outcomes regarding clinical pregnancy rate and implantation, and even a slightly compromised live birth rate when compared with FRBT. Moreover, a higher occurrence of cesarean Section (88.89% versus 71.29%, P < 0.05) and a shorter gestational age (262.04 ± 14.99 days versus 268.06 ± 14.07, P < 0.05) were also found. Nevertheless, the risk of small for gestational age and large for gestational age, and the neonatal birth weight were comparable.

CONCLUSIONS

VTCE blastocysts' transfer results in a comprehensively moderate outcome, which is an acceptable option for patients. Our results can provide efficient value for patients' counseling. Furthermore, these findings indicate directions for exploring the mechanisms of low birth weight and short gestational age.