Misconceptions about Stored Frozen IVF Embryos

Return to Human Cloning and Stem Cell Research

Myth: Nearly 400,000 embryos derived from in vitro fertilization are currently frozen and destined to be destroyed.

Reality: The “400,000 frozen embryos” estimate originates from a study published by the RAND Corporation in 2002.1  While the researchers concluded that nearly 400,000 embryos have been frozen and stored since the late 1970’s, they also confirmed that only a small fraction of those 400,000 embryos are available for research.  Below is a breakdown of the anticipated use of the 400,000 stored embryos.

  • 88.2% (352,800) are being stored for future family building. 
  • 2.8% (11,200) have been designated for research by the parents. 
  • 2.3% (9,200) have been placed for adoption by the parents. 
  • 2.2% (8,800) are designated by the parents to be discarded. 
  • 4.5% (18,000) are held in storage as a result of lost contact with the parent, parent death, abandonment, or divorce. 

In the United States , the decision regarding what to do with extra IVF embryos rests with the parents who produced them.  Whether or not the parents plan to implant their unborn children in utero, their IVF embryos are not public property, and therefore, these embryos cannot be automatically marked for scientific research.  No amount of funding (government or private) will change the fact that the parents have decided to dispose, preserve, or place their embryos for adoption.

The 2.8 % (11,200) of the 400,000 stored embryos designated for research are available to privately funded scientists.  However, the RAND researchers admit that less than 1,000 of those 11,200 are usable for research.  Furthermore, RAND estimates that those 1,000 will only yield, at most, a few hundred stem cell lines for several reasons:

The “best quality” embryos are transferred to the mother during fertility treatment cycles, and therefore, the remaining embryos are usually not of the “highest quality.” 
Some of the embryos have been in storage for many years.  At the time the embryos were created, laboratory cultures were not as conducive to preserving embryos. 
Some embryos will perish in the thawing process.  RAND researchers estimated that 65% of the approximately 11,000 embryos would survive the thawing process, resulting in 7,334 embryos.  Of those, about 25% (1,834 embryos) would likely be able to survive the initial stages of development to the blastocyst stage (at least 5 days old) required for stem cell extraction.  Even fewer could be successfully converted into embryonic stem cell lines.  For example, researchers at the University of Wisconsin needed 18 blastocysts to create 5 embryonic stem cell lines, while researchers at The Jones Institute used 40 blastocysts to create 3 lines. 

Myth: These embryos are an ideal reserve, if donated with informed consent by both parents, to replenish that lines that have been lost, without crossing the moral line of unethically harvesting and destroying human embryos.

Reality: The 78 stem cells lines supported by the government have not been lost; scientists are currently performing research on 23 of those lines, and the remainder of the lines are being held for future research.2  Thus, there is no need for replacements.

In the May 2004 issue of Scientific American, embryonic stem-cell-researchers Robert Lanza and Nadia Rosenthal concluded that hundreds of thousands of embryonic stem cell lines would be needed to establish a bank of cells with immune matches for patients; creating that many lines would require millions of discarded embryos from IVF clinics.  As noted previously, only approximately 1,000 of the 400,000 stored IVF embryos will be usable for research.  This falls short (by millions of embryos) of what Lanza and Rosenthal estimate will be needed for patient matches.  Cloning millions of human embryos would be the only alternative to start the hundreds of thousands of stem cell lines needed for a stem cell bank.  Although most Americans are uncomfortable with cloning human beings, scientists and advocacy groups are already asking the federal government and the public to support and fund the cloning of human embryos for research purposes.

Myth: If IVF embryos are destined for disposal anyway, they should be used to benefit others.

Reality: This argument assumes that the life will be lost anyway, as the embryo is destined to be thawed and discarded at the choice of the conceiving parents, and therefore, such a loss should be redeemed by using that life for research purposes.  Such an argument would equally support research on prisoners condemned to death, giving researchers the liberty to remove their transplantable organs with or without consent, or on patients nearing their death in nursing homes and hospitals (after all these patients are going to die anyway).

A true interest in the stewardship of IVF embryos would promote embryo donation and adoption.  Thousands of infertile couples cannot participate in expensive fertility treatments due to health reasons or a lack of finances.  Organizations such as Snowflakes Embryo Adoption Program (www.snowflakes.org) assist such couples with adopting and implanting embryos remaining from other parent’s fertility treatments.  9,200 of the 400,000 stored IVF embryos are in the adoption process due to the efforts of such organizations.

1. Hoffman S., Zellman G., Fair C., et al. “Cryopreserved embryos in the United States and their availability for research.” Fertility and Sterility 2003; 79: 1063-1069.
2. NIH Human Embryonic Stem Cell Registry: Cell Lines Not Yet Available. www.stemcells.gov/research/registry/unavailable.