What parameters affect live birth outcomes after frozen blastocyst transfer?

This study investigated the factors affecting the live birth rate (LBR) after frozen blastocyst transfer (FBT). 

They found that a higher body mass index (BMI; a measure of weight in relation to height) and a high miscarriage rate (MCR) were associated with lower LBR after FBT. 

Assisted reproduction (AR) is becoming more common. New technologies have been developed to improve the success of AR. One technique is pre-implantation genetic testing for aneuploidy (PGT-A). This test measures the number of chromosomes in an embryo. If there are extra or missing chromosomes this can lead to a failed pregnancy.

Embryos are allowed to grow to a certain stage (blastocyst). Cells are taken from the outer layer of the blastocyst (trophectoderm biopsy, TB). An embryo with the correct number of chromosomes is called an euploid embryo. After PGT-A embryos have developed into blastocysts. They are commonly frozen before transfer. This is called frozen euploid blastocyst transfer (FEBT).

PGT-A does not always result in improved pregnancy outcomes. PGT-A is a complicated technology. There are many different processes. Some processes differ between labs. External factors may also affect pregnancy outcomes. Some studies suggest that patient characteristics may have an effect on live birth rate (LBR). It is unclear what factors affect LBR after PGT-A and FEBT.

This study included 707 FEBT procedures after PGT-A. Patient data were obtained from a database. Information on the PGT-A and FEBT procedures were compared. Pregnancy outcomes including LBR and previous miscarriage rate (MCR) were analyzed. 

Patients with higher BMI had lower LBR. The odds of a LBR was 21% lower in patients with a BMI between 24-29 kg/m² compared to those with a normal BMI. The day of the TB also affected LBR. TB on Day 6 was associated with a 66% reduced odds of a LBR. A high number of previous miscarriages was associated with a 26% reduction in the odds of a LBR. 

The authors concluded that a higher BMI and MCR were associated with lower LBR after FEBT.

This study was based on medical records. Some information might have been missing. Further studies are needed for stronger evidence.

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