Polygenic Embryo Selection

Conventional IVF involves the use of morphological grading, commonly using Gardner scores, to prioritize embryos for transfer. Morphological grading is a well established method to improve implantation rates, with better morphological scored embryos having a higher success than lower scoring embryos. Morphology-based selection is also employed following preimplantation genetic testing for aneuploidy (PGT-A), which is now used in over 60% of all IVF cycles in the United States.

More recently, polygenic scoring (PRS) of embryos has been introduced to provide additional information on disease risks and trait probabilities, allowing patients to utilize an alternative method of embryo selection. While there is no prospective study evaluating the utility of PRS, longitudinal studies on over 20,000 sibling pairs and on millions of adults have demonstrated significant disease risk reduction.

One common concern over the use of PRS in place of morphology based selection is the potential impact of implantation and delivery rates. For example, in some cases, the embryo with the lowest risk of a disease may not be the best morphology in the cohort of embryos available for transfer. The question of whether genetic based selection results in lower success rates than morphology based selection has not been evaluated in a prospective observational study. Some retrospective data exist in the context of sex selection. For example, patients using PGT-A may decide to transfer an embryo with their preferred sex (male or female) instead of choosing based on morphology alone. One such study indicated no significant difference in delivery rates between sex and morphology based selection. While this outcome remains surprising to many, one factor that is not always considered is that genetic selection does not always lead to transferring an embryo with the worst morphology. However, similar studies have not been published to corroborate these findings.

This study will evaluate whether IVF success rates after PRS based embryo selection are different from morphology based embryo selection and whether polygenic disease risk is correlated with embryo morphology.