The main difference between embryo freezing and egg freezing is the presence of sperm. In embryo freezing, eggs are retrieved and then fertilized by sperm to create embryos, and the embryos are analyzed using preimplantation genetic testing (PGT), then cryopreserved until ready to be used to attempt pregnancy. Embryo freezing may be a good option for couples who want to delay parenthood, as well as single women and lesbian couples who have chosen a sperm donor, but do not want to get pregnant right away.
Embryo freezing along with preimplantation genetic testing (PGT) is becoming increasingly popular for patients going through a cycle of IVF. Instead of transferring a fresh embryo three to five days after fertilization, the embryos undergo preimplantation genetic testing so that the healthiest embryos can be identified. The embryos are frozen while the genetic testing is performed by an outside specialty laboratory. Once the PGT results come back within 1-2 weeks, the healthiest embryo is identified, thawed, and transferred to the patient’s uterus. This timing also allows the body’s hormone levels to stabilize after being on fertility medications. There is growing evidence that frozen embryo transfer with PGT can significantly improve implantation rates.