What is a mosaic embryo?

A mosaic embryo is an embryo that contains a mix of normal and abnormal cells. These abnormalities can result from errors that occur during cell division early in development. Mosaic embryos can occur naturally and are not uncommon in the process of in vitro fertilization (IVF) and other assisted reproductive technologies.

Mosaic embryos are often classified based on the percentage of abnormal cells they contain. Low-level mosaicism, where only a small percentage of cells are abnormal, may have a lower impact on the potential for successful implantation and pregnancy compared to high-level mosaicism.

The presence of mosaic embryos can complicate the process of selecting embryos for transfer in IVF, as it is not always clear how much of an impact the mosaicism will have on the embryo's ability to develop into a healthy pregnancy. Some clinics may choose not to transfer mosaic embryos due to the potential risks, while others may offer them as a viable option for transfer.

Research on mosaic embryos and their potential impact on fertility and pregnancy outcomes is ongoing, as scientists and fertility specialists work to better understand the complexities of embryo development and genetic abnormalities.