Comparing the outcomes of two methods of embryo transfer

This study investigated the fertility outcomes (FOs) after transfer of vitrified-thawed cleavage embryos (VTCE).

They found that VTCE was associated with positive and negative FOs. 

Assisted reproductive technology (ART) is used to treat infertility. Initially, oocytes (eggs) are harvested and fertilized in a lab (in vitro). This produces an embryo. The embryo is allowed to grow in vitro for up to 5 days. Then embryo transfer (ET) may be performed. This is called a fresh ET (Fr-ET). Embryos can also be frozen and transferred at a later date. This is frozen ET (Fz-ET).

After 5 days an embryo undergoes a process called cleavage. It then becomes a blastocyst (BC). Some doctors prefer to transfer BCs instead of embryos. There may be better fertility outcomes (FOs) with blastocyst transfer (BCT). It is also possible to freeze BCs using a process called vitrification. At a later stage, blastocysts can be thawed and transferred. It is unclear if the transfer of vitrified-thawed cleavage embryos (VTCE) is associated with positive FOs. 

This study included 374 patients undergoing ART. They were separated into 3 groups, depending on the type of ET. Group 1 involved 155 VTCE transfers (VTCET). Group 2 involved 4904 Fz-ET and group 3 involved 1014 Fr-ET. The authors compared FOs between the 3 groups. These included miscarriage, clinical pregnancy rate (CPR), live birth rate (LBR) and cesarean section rate (CSR). Other outcomes included birth weight (BW) of the newborn. 

VTCET was associated with a lower risk of early miscarriage compared to Fz-ET (8.82% vs 19.7%). It was also associated with lower fetal birth weight compared to Fz-ET. There was no difference in LBR or CSR between VTCET and Fz-ET.

VTCET was linked to a lower CPR, implantation, and LBR compared to Fr-ET. VCTET was more likely to result in a cesarean section than Fr-ET. 

The authors concluded that VTCE was associated with similar FOs compared to Fz-ET and slightly poorer outcomes compared to Fr-ET.

The number of VTCET cycles included in this study was low. This was a study based on medical records so some information was not available. More investigation is needed. 

If you have any concerns regarding infertility and ART please consult with your physician.