Embryo Freezing

The prospective mother’s ovaries are artificially stimulated in new IVF rounds to generate a larger number of mature eggs. The eggs are then extracted via a process known as a follicular puncture or ovum pick-up (OPU) and then fertilized in the lab using the husband’s or donor sperm.

In in vitro fertilization (IVF), embryo freezing is a process in which embryos are preserved for future use by being frozen and stored at very low temperatures. Embryo freezing is typically done after the IVF fertilization process, when embryos are at the blastocyst stage of development (usually around 5-6 days after fertilization). The embryos are carefully prepared for freezing by being placed in a solution that helps to protect them from damage during the freezing process. They are then frozen using a process called vitrification, which involves rapidly cooling the embryos to very low temperatures (usually around -196°C/-320°F) using liquid nitrogen.

Embryo freezing can be used to preserve embryos that are not transferred to the woman’s uterus during the initial IVF cycle, either because there are more embryos than can be safely transferred or because the woman and her partner want to reserve some embryos for future use. Embryos can be thawed and transferred to the woman’s uterus at a later time, either in the same IVF cycle or in a future cycle. Embryo freezing can also be used to preserve embryos for other purposes, such as for use in research or for donation to another couple or individual.