Fertility Preservation

Successful egg freezing is an advancement that has eluded reproductive endocrinologists for the first three decades of in vitro fertilization. The major stumbling block was ice crystal formation that damaged the frozen egg.

For some time, the doctors at Houston IVF and CCRM have been studying competing technologies designed to avoid this problem. A process called vitrification uses a cryoprotectant to make water in the egg harden without formation of ice crystals. This technique has now been demonstrated to yield better pregnancy rates than other techniques such as slow freezing.

Our clinical trials using vitrification have demonstrated satisfactory freezing and thawing of eggs resulting in live births. Success has been improved by recognizing that directly injecting a sperm into the thawed egg, a technique called intracytoplasmic sperm injection (ICSI), is required for good fertilization rates after thawing.

We are excited to announce that Houston IVF has successfully implemented a method of cryopreservation which has allowed us to achieve high success rates with egg freezing. Vitrification, unlike slow cooling which has been used for freezing over the past 20 years, avoids the damage to the cell invoked by ice crystal formation, as well as the “chilling” effects seen with slow cooling. With vitrification, embryos are taken from room temperature to -196º C in a fraction of a second using high concentrations of cryoprotectants.

At Houston IVF, we performed an initial clinical trial freezing oocytes for patients who desired pregnancy in the near future so that we would be able to thaw those eggs in a short time and determine survival rates, fertilization rates, and pregnancy rates. With this new method of vitrification, we have achieved egg survival rates of approximately 80%, fertilization rates of over 80%, and pregnancy rates above 50%.

Due to the success of our study with oocyte vitrification, Houston IVF is now able to offer fertility preservation services through egg-freezing to appropriately evaluated patients and oocyte donor candidates. It is important to note that oocyte vitrification is still considered to be an experimental technology by the American Society for Reproductive Medicine. Houston IVF is pleased to have sufficient internal clinical data, to justify the use of this technology in appropriately evaluated women desiring fertility preservation.

The types of patients who may want to access this technology include young women who want to preserve their fertility due to career or lifestyle choices. Such patients may know that having children will not occur until much later in life and are concerned that their fertility may be compromised at that point. The ability to freeze their oocytes at a young age will give them the opportunity to conceive at a later time which may be more appropriate for them.

The second group of patients who are candidates for egg freezing are those young women recently diagnosed with cancer who are not in a relationship. Since most cancer treatments involve radiation, chemotherapy, or a combination of both, ovarian function is often compromised rendering the patient infertile. If the patient is single, the use of donor sperm to create embryos is typically not a first choice and represents an extremely difficult emotional decision. It would, therefore, be much more desirable to freeze her unfertilized eggs and have the opportunity in the future, once her treatment is completed and she is in a relationship, to use her partner’s sperm to fertilize her eggs and have children.

For a better understanding, watch the video below of egg freezing at Houston IVF.

The national success rate for live births from frozen eggs has only been about 2%, and a 2009 study showed only 936 babies had been born from frozen eggs worldwide to date. Embryologists from our Colorado center went to Japan to learn these techniques, which have proven significantly more successful. 

First In Texas

One couple has opened the doors for many other women to preserve their fertility. "After it hit us what it really meant, we were kinda blown away by it. Still today when we try to explain to somebody what it means, they just say, 'OK,'" said the patient.

Five-pound Alba and four-pound Joseph are a gift to their doting parents, Yvonne and Chris Pena. Alba and Joseph are the first babies born in Texas from frozen human eggs.

Embryo Preservation

Some couples are fortunate enough to collect a large number of embryos from one egg collection. Any remaining viable embryos that are not transferred into the woman's uterus during the month of treatment may be frozen ("cryopreserved") in small tubes and kept in storage in the embryo laboratory for future use. This allows the patient to limit the number of embryos transferred "fresh" without sacrificing the chance that the unused embryos could lead to a pregnancy. The embryos may be kept in storage for several years. By transferring frozen-thawed embryos into the uterus, some patients have achieved 2-3 pregnancies in different years from just one egg collection.