Texas Fertility Center San Antonio

Gamete Freezing

Gamete freezing is long-term storage for eggs, sperm or embryos

Freezing embryos

the traditional way to preserve fertility was to freeze embryos.  Eggs are removed after ovarian stimulation and fertilized in the laboratory.  The embryos that are growing and meet criteria by Day 5, 6 or 7 are frozen or cyropreserved for future use. These embryos have an excellent chance of surviving the freeze/warming process and creating a pregnancy.

Freezing embryos allows a pregnancy to be achieved at some point in the future.  Because embryos can be frozen, more than one pregnancy may be achieved with one retrieval.  Cryopreservation is done with a process called vitrification.  This process is safe and tolerated well by embryos.

Egg freezing

Freezing eggs or oocytes is relatively new because new technology has allowed successful freezing and thawing of human eggs with excellent pregnancy rates. Eggs are more fragile than embryos and proved more difficult to freeze.  After ovarian stimulation, eggs are removed from the body and can be frozen for later use.  When the woman is ready to conceive, eggs are thawed and fertilized. Eggs can be kept frozen indefinitely.

Women who choose to freeze eggs include women of advanced reproductive age who wish to defer starting their pregnancy until their fertility will be declined, women with a diagnosis of cancer or some other medical problem requiring chemotherapy or other long-term treatment that precludes pregnancy.

Sperm freezing

Sperm can be frozen for those undergoing an IVF procedure at San Antonio IVF or who will have an insemination at Texas Fertility Center. The reasons for freezing sperm vary, but common reasons for freezing sperm include:

  • planned chemotherapy or radiation treatment for cancer that has potential to dramatically reduce sperm production
  • as a back-up for IVF or IUI if the male will be out of town or anticipates difficulty in producing a specimen
  • as a second source of sperm when there severe male factor infertility