We continue our efforts to inform you about developments in reproductive medicine, as well as provide insight into the often challenging journey of fertility patients. This letter discusses: Cryopreservation of Embryos and Choices about Disposition.
The technology for freezing human embryos has been available for more than 25 years. About 20% (700,000 out of 3.5 million) of the offspring born worldwide from In Vitro Fertilization (IVF) cycles are from cryopreserved (frozen) embryos or oocytes. In the past 10 years the technology has improved significantly, allowing more frozen embryos to survive the thawing process and resume developing. About 35% of all IVF cycles using fresh embryos result in live births. If frozen embryos are used, about 27% result in live births.
Providing the option to freeze embryos is an excellent solution to the dilemma of deciding how many embryos to transfer to a woman’s Uterus. The most common reasons to freeze embryos are to avoid multiple pregnancies and/or to have additional embryos available for later use. The American Society for Reproductive Medicine (ASRM) has published practice guidelines for how many embryos to transfer to a prospective mother’s uterus, based on the age of the woman providing the eggs and the degree of Embryo development (Fertility and Sterility, Vol. 86, Sup. 4, S51-52, Nov., 2006). There is a strong trend in Assisted Reproduction Technology (ART) to transfer fewer embryos, including recommending elective single embryo transfer (eSET), when embryos appear well developed. Embryos are frozen for future use when the woman’s uterine lining is not sufficiently prepared, the woman had developed severe ovarian hyperStimulation, or to preserve fertility. For a woman facing chemotherapy that may damage the ovaries, freezing embryos may be her best or only chance to have a genetically related child after her treatment.
Patients using ART are often very anxious to achieve a successful pregnancy, and may attempt to pressure their physician to transfer more embryos, in the hope that at least one will “take”. Financial strain, often depending on what medical insurance covers, is another factor. In addition, many patients underestimate the actual medical and psychosocial risks of multiples. In fact, about 40% of IVF patients will say that a multiple birth, usually twins, is what they are hoping for.
It is impossible to predict the details of any IVF Cycle with accuracy, and this adds to the stress of making advance decisions about freezing embryos or inseminating a set number of eggs. IVF is a multi-step process that occurs over several weeks. The woman’s ovaries are stimulated with hormones and she is closely monitored as multiple follicles containing eggs develop. The eggs are retrieved vaginally and sperm is introduced in the embryology lab to fertilize the eggs. Embryos develop in the lab for several days, usually no more than 7, with embryo transfers occurring on day 3 or day 5. Remaining embryos may be frozen, if the patients have chosen that option. What is not predictable is how many eggs will be retrieved, how many will fertilize, how many will develop into embryos with a high potential to implant, and how many embryos will be suitable to freeze. While it is estimated that only 35-40% of IVF cycles result in frozen embryos, it is also possible to have many “extra” embryos, especially if an egg donor was utilized. Many patients want to have extra frozen embryos they can use if the fresh embryo transfer fails. They will pay far less for a frozen embryo transfer than for a new IVF cycle, and fewer drugs are needed. Patients also find it attractive to have embryos stored for them when they want another child. Today, most frozen embryos survive the thawing process and resume developing, and the outcome statistics for fresh and frozen embryos are very comparable.
Many IVF patients struggle with the implications of freezing their embryos. In advance of a cycle, patients are asked to decide about freezing and are also asked to state what the clinic should do with embryos if the patients cannot be located, die, or divorce. Patients struggle with the ethical and moral issues of freezing embryos, and some seek pastoral counseling. Yet, the powerful desire to create a family can overwhelm the moral qualms of reproductive decisions. Almost all IVF patients sign the consent to freeze embryos.
When people have the family they desire and do not want more children, the decision about the disposition of their embryos becomes a necessity. Most IVF programs impose a time limit, typically 5 years, for patients to decide how they will use their embryos. The clinic sends a storage bill each year, usually around $700, an annual reminder about the need to decide. The choices for embryo disposition, which may vary depending on the IVF center and which state it is in, are discard, donation to scientific research, or donation to another family. There are also facilities that will accept embryos for long-term storage, for people who need more time to decide.
At Fertility Centers of Illinois®, we make every effort to help people think about these decisions before embryos are created. As the staff psychologist, I am available to our patients (or former patients) who have embryos and are struggling with this complicated decision. Patients desiring to donate embryos to a family can utilize the two programs that are the best known in the United States, Snowflakes and the National Embryo Donation Center, or they may locate the recipients on their own. Patients desiring to donate to science are referred to various research programs by our embryologists.