In vitro fertilization remains one of the most cutting-edge procedures for treating infertility. New discoveries provide opportunities to advance technologies and provide even better results to patients. Recent research regarding preimplantation genetic diagnosis (PGD) asks fertility specialists to rethink when they perform PGD—is it better to screen developing embryos on day 3 or day 5? You’d be surprised at the difference two days can make.

Understanding PGD

Preimplantation genetic diagnosis (or preimplantation genetic screening) is a standard biopsy procedure performed on embryos prior to implantation to ensure genetic normalcy and a healthy baby. The type of PGD determines the thoroughness of the screening. For example, a FISH (Fluorescent In-Situ Hybridization) PGD could only look up a mere fraction of the chromosomes, up to 12. In the past, FISH was the standard testing, but reliability and accuracy were questionable, quickly forcing the test into obsolescence.

Micro Array is the newest type of PGD that allows an accurate screening of all 23 pairs of chromosomes.

Why Use PGD?

All women have some risk of having a pregnancy with chromosomal abnormalities, a risk that dramatically increases with age. PGD gives prospective mothers at a more advanced age or with dangerous hereditary conditions the option of analyzing chromosomal normalcy of embryos prior to implantation. This ensures a healthy baby and a smooth birthing process.

The most common cause of miscarriage is chromosomal abnormality. Patients who have experienced a miscarriage in the past may consider a PGD screening to avoid future complications. Patients with a family history of genetic disorders can choose to exclude affected embryos from being implanted.

Timing is Everything

Currently, a typical preimplantation genetic diagnosis biopsy is performed on the embryo at day 3 of development. At this point, the embryo is tiny—composed of only six to eight cells—and only one cell is removed for genetic diagnosis.

However, new research released at The American Society of Reproductive Medicine’s 67th annual meetingshows that waiting until day 5 may be much more effective and yield much more promising results. By day 5, the embryo is in the blastocyst stage and has undergone the first step of differentiation to form the trophectoderm. This eventually becomes the placenta and the inner cell mass which then becomes the fetus.

The embryo contains almost a hundred cells by day 5, which means more cells can be removed for a much safer, more robust procedure. Additional research shows that abnormalities seen at day 3 can actually correct themselves by day 5. Performing the PGD on day 5 has led to significant improvements in implantation rates and excellent results for patients.

Here at La Jolla IVF, we took this research into great consideration. We perform PDG at day 5, and transfer the embryo on day 6. It’s exciting to work in the ever-changing reproductive healthcare industry, consistently taking into account new research that helps our procedures be more successful for our patients.

Check out our recent press release about day-6 embryo transfers