# Comment on “Reproductive Outcomes of Transferring Blastocysts Derived From Frozen–Thawed Cleavage Embryos: A Systematic Review and Meta‐Analysis”

## TL;DR

This paper comments on a study comparing two embryo transfer methods after freezing, finding similar birth weights but better pregnancy outcomes with one method.

## Contribution

The paper emphasizes the importance of transparent reporting and target-trial emulation for clinical decision-making in embryo transfer.

## Key findings

- FT-CDB showed higher odds of clinical pregnancy and live birth compared to DFB.
- Neonatal birth weight was similar between the two transfer methods.
- The paper highlights the need for target-trial emulation and transparent reporting.

## Abstract

Tran et al. synthesized seven studies (n = 2,057) comparing frozen–thawed cleavage embryos cultured to blastocyst then transferred (FT‐CDB) with direct frozen–thawed blastocyst transfer (DFB) in vitrification cycles. They found higher odds of clinical pregnancy and live birth with FT‐CDB and no difference in neonatal birth weight. We discuss implications for laboratories weighing thaw‐and‐extend versus direct blastocyst transfer, emphasizing estimands per oocyte retrieval/intention‐to‐treat, workflow metrics, and laboratory‐level covariates. Context from randomized controlled trials (RCTs) and systematic reviews suggests cumulative live birth may converge, highlighting the need for target‐trial emulation and transparent reporting to inform clinical decision‐making and guideline development.