ACOG Committee Opinion
Number 347, November 2006
(Reaffirmed 2008)

Committee on Ethics
PDF Format

Using Preimplantation Embryos for Research*

ABSTRACT: Human embryonic stem cell research promises an increased understanding of the molecular process underlying cell differentiation. Transplantation of embryonic stem cells or their derivatives may, in the future, offer therapies for human diseases. In this Committee Opinion, the American College of Obstetricians and Gynecologists (ACOG) Committee on Ethics presents an ethical framework for examining issues surrounding research using preimplantation embryos and proposes ethical guidelines for such research. The Committee acknowledges the diversity of opinions among ACOG members and affirms that no physician who finds embryo research morally objectionable should be required or expected to participate in such research. The Committee supports embryo research within 14 days after evidence of fertilization but limits it according to ethical guidelines. The Committee recommends that cryopreserved embryos be the preferred source for research but believes that the promise of somatic cell nuclear transfer is such that research in this area is justified. The Committee opposes reproductive cloning. Intended parents for whom embryos are created should give informed consent for the disposition of any excess embryos. The donors of gametes or somatic cells used in the creation of such tissue should give consent for donation of embryos for research. Abandoned embryos should not be accepted for research. Potential research projects should be described to potential donors as much as possible. Donation of embryos for stem cell research requires specific consent. The Committee believes that compensation for egg donors for research is acceptable, consistent with American Society for Reproductive Medicine guidelines.

The human embryo has long attracted the interest of researchers. Initially, scientists studying embryos hoped to better understand human pregnancy and embryonic development. Later, with the emergence of assisted reproductive technologies such as in vitro fertilization (IVF), embryo research focused on optimizing pregnancy rates and outcomes. Most recently, research has targeted the stem cells derived from embryos because stem cell research promises an increased understanding of the molecular process underlying cell differentiation (the process of acquiring characteristics of specific tissues and organs). Transplantation of embryonic stem cells or their derivatives may, in the future, offer therapies for human diseases. These possibilities, coupled with the demonstration in 1998 that stem cells could be isolated from either the inner cell mass of blastocysts or fetal germ cell tissue, have sparked public debate on the ethical foundation of stem cell work specifically and embryo research in general. The urgency of these questions makes it timely both to review the moral issues raised by human embryo research and to consider appropriate guidelines for the ethical conduct of these endeavors.

*Update of "Preembryo Research" in Ethics in Obstetrics and Gynecology, Second Edition, 2004
Terms defined in the glossary appear in bold type.

The Committee on Ethics acknowledges the diversity of opinions regarding these topics among members of the American College of Obstetricians and Gynecologists (ACOG), a diversity mirroring that in society at large. These diverse positions range from complete rejection of all human embryo research to approval of the deliberate creation of human embryos for research. Even among those who accept embryo research on ethical grounds, there is disagreement about the conditions under which it may ethically be conducted.

The purpose of this Committee Opinion is to present a relevant ethical framework within which to view contemporary embryo research and to propose ethical guidelines for such research. The opinion focuses specifically on issues relating to research using preimplantation embryos. The Committee recognizes that the science of this field, especially the science of stem cell research and therapy, is changing rapidly and anticipates that future changes will require revisiting past issues and either modifying previous guidelines or creating new ones in order to address formerly unimagined possibilities.

Historical Perspective: Policies and Regulation

Oversight and regulation of research involving human reproduction, especially that involving fertilized eggs and embryos, have a long and contentious history linked both to the politics of abortion and to the introduction of IVF into clinical practice (Fig. 1). Certainly, clinical progress with assisted reproductive technologies requires research, yet performing such research raises important questions about how the needed tissues should be obtained and treated.

Figure 1

Several events and issues, including the U.S. Supreme Court's decision on abortion in Roe v. Wade and revelations of abuses in human subjects research, led Congress in 1974 to establish the National Commission for the Protection of Human Subjects. On the basis of guidelines proposed by the National Commission in 1975, the then Department of Health, Education, and Welfare issued regulations for federal funding of research involving human fetuses. These regulations defined the fetus as the product of conception from the time of implantation on (1). The regulations also recommended the appointment of an ethical advisory board to examine unresolved questions. The Ethics Advisory Board (EAB) was appointed in 1978, shortly before the first birth from IVF, with a mandate to review both IVF research and research using embryos resulting from IVF.

In its 1979 report, the EAB stated, "The human embryo is entitled to profound respect; but this respect does not necessarily encompass the full legal and moral rights attributed to persons" (2). The EAB statement supported the ethical acceptability of research to study and develop the safety and efficacy of IVF and embryo transfer techniques used for the treatment of infertility. The EAB also accepted the use of gametes of informed, married, and consenting donors in such research, provided that developing embryos were not sustained longer than 14 days in vitro, a limit chosen in part because the primitive streak is formed at this juncture. In its statement, the EAB did not distinguish between "excess" embryos from IVF therapy and embryos "created solely for research." In fact, the EAB implied that research may require the creation of embryos that, because of concerns for safety, would never be intended for transfer.

Because of public and political opposition to embryo research, however, EAB guidelines were never implemented, and the board's charter was allowed to expire in 1980, effectively imposing a moratorium on federal funding of IVF and embryo research because existing legislation required the oversight of an ethical advisory board as a prerequisite. Thus, any embryo research conducted in the United States at that time had to use private or university funding and often was undertaken in the context of infertility treatment. Recognizing the ethical and regulatory challenges associated with the conduct of research outside of federal oversight, the Ethics Committee of the American Fertility Society (now American Society for Reproductive Medicine [ASRM]) issued specific guidelines for conducting such work (3–5). The ASRM committee endorsed embryo research but, echoing earlier guidelines, recommended that human embryos not be maintained for research beyond the 14th day after fertilization (3, 4). The same group noted that because of the "high moral value" accorded to preimplantation embryos, research using these tissues required "strong justification," but later the group also recognized that some "studies may require the production of human [preimplantation embryos] as an integral part of the analysis" (5). In the face of ongoing debate at a federal level, privately funded research in the United States has been influenced by these ASRM recommendations.

Federal funding of embryo research was further limited in 1995 with passage of the Dickey Amendment, in which Congress prohibited the use of any federal funds for "creation of a human embryo(s) for research purposes or research in which a human embryo(s) are destroyed, discarded, or knowingly subjected to risk of injury or death for research purposes" (6). A similar Dickey Amendment has been attached to the appropriations bill for the Department of Health and Human Services in every year since. Thus, by the mid-1990s, although the pursuit of embryo research was not prohibited by the federal government, the ban on federal funding limited its conduct.

The isolation of stem cells from embryonic and fetal tissues in 1998 engendered debate about how existing regulations and guidelines should guide research with such cells. In 1999, the general counsel of the Department of Health and Human Services during the Clinton administration argued that the literal language of the Dickey Amendment permitted funding of embryonic stem cell research as long as the stem cell line had been derived through research that was not federally funded. Under this interpretation, the use of embryonic stem cells would not constitute research "in which an embryo was destroyed, discarded, or subjected to risk of injury." That same year, the National Bioethics Advisory Commission, a group charged with identifying "broad principles to govern the ethical conduct of research," recommended federal support for stem cell research using embryos remaining after infertility treatments, but opposed creation of embryos specifically for research (7).

In contrast to these recommendations, in August 2001, the Bush administration announced what remains the current federal funding policy for embryonic stem cell research (8). This policy permits federal funding only for work using stem cell lines in existence on August 9, 2001; derived from excess embryos created solely for reproductive purposes; and made available with the informed consent of the donors. Although critics note several important limitations that these regulations place on U.S. researchers (see "Are There Alternatives to Using Preimplantation Embryos for Research?"), the regulations remain active and unchanged as of late 2006. However, funding of stem cell research using fetal tissues (eg, obtained from abortus materials) is still permitted—although perhaps less frequently performed—under the Fetal Tissue Transplantation Research Act (9) and guidelines established during the Clinton administration.

Current Clinical Practices

Practices and policies for the care of patients are likely to inform attitudes and future guidelines regarding the use of embryos for research. Before addressing specific questions on stem cell and other embryo research, established clinical practices involving gametes and embryos are noted briefly. A complete review of each area and its moral foundation is, however, beyond the scope of this Committee Opinion.

In Vitro Fertilization

Current IVF techniques often result in the creation of more embryos than can be transferred safely to a woman's uterus for implantation. Practitioners and patients should anticipate this possibility by having patients prospectively consider the matter and detail their wishes regarding such excess embryos. Many have advocated, for example, "prefreeze agreements" in which patients indicate their wishes for disposition of frozen embryos in the event of life-changing circumstances such as death or divorce. Advance discussions and agreements do not, however, preclude the need to continue discussion at the time final decisions regarding frozen embryos are made, for researchers have demonstrated the difficulties couples have processing this counseling at the time of creating embryos for reproductive purpose (10). The ASRM and individual states recognize the right of appropriate individuals to make such decisions regarding embryos. Such options include extended freezing, destruction of embryos either by failing to transfer or freeze or later thawing without transfer, and donation for attempted implantation by another individual or couple. The ACOG Committee on Ethics recognizes all of these options as reasonable and appropriate and in so doing accepts that it is the individual or couple who created the embryos, either with their own or donor gametes, who are entitled to make these decisions. This current Committee Opinion outlines ethical considerations related to the option of using preimplantation embryos for research.

Gamete Donation

Both egg and sperm may be donated either anonymously or by directed donation to specific individuals or couples. Donated gametes are widely used for infertility treatment, and sperm and egg obtained in excess of what is needed for such treatments have, with appropriate consent, later been used for research. Gametes also have been donated for research purposes only, separate from any plans for infertility treatment and therapy, and the Committee on Ethics supports such donation. In the past, research using gametes has included studies designed to optimize IVF techniques and work examining gamete cryopreservation. The donation of oocytes for research purposes is controversial, however, and has raised what ASRM terms "special concern" (5) because of the risk, pain, and side effects involved in the process of egg donation and because of concerns about possible exploitation of donors.

Embryo Research: Ethical Questions

What Is the Moral Status of the Embryo?

In debates about the ethics of embryo research, the central ethical question historically has focused on the embryo's "moral status" and whether the embryo is deserving of the same rights and protections as a child or adult person. This Committee Opinion is based on the view that although the preimplantation embryo merits respect, its moral status is not equivalent to that of a human being. Scientific information alone will never resolve questions about the embryo's moral status. However, several distinguishing features of preimplantation embryos inform the evaluation of the moral status of the embryo and, hence, the ethical arguments concerning embryo research. Figure 2 outlines the development of pregnancy from gamete to fetus, a path that highlights the distinguishing characteristics of preimplantation embryos:

  1. Early embryonic cells are undifferentiated. Until the blastocyst stage, each cell is totipotent, having the capacity to differentiate into any of the cell or tissue types of the fetus or to form placental and other extra-embryonic tissues. Each of the cells of the inner cell mass of the blastocyst is pluripotent, with the capacity to become any of the cell or tissue types of the fetus, but at this stage, these cells form a collection of undifferentiated cells rather than a unified organism.
  2. Embryos at early stages lack individuation. This is evidenced by research demonstrating that, up to at least the 8-cell stage, one or more blastomeres can be removed from the embryo (eg, as for preimplantation genetic diagnosis [PGD]) and the remaining blastomeres can still produce a complete human being. Also, from the initial stages of cell division until the formation of the primitive streak, the embryo is capable of dividing into more than one entity (ie, twinning). Only after this period has differentiation of embryonic cells advanced to the point that separation can no longer result in two or more individuals (11–13).
  3. The formation of the primitive streak at day 14 marks the beginning of the differentiation of cells into the various tissues and organs of the human body. Before the appearance of the primitive streak, the cells of the embryo are undifferentiated and pluripotent. Recognizing this biologic landmark, many, now including the ACOG Committee on Ethics, have recommended limiting embryo research to the first 14 days after fertilization.
  4. If the preimplantation embryo is left or maintained outside the uterus, it cannot develop into a human being. Continuing potential for life exists if, but only if, the embryo is transferred to the uterus for implantation (this potential will have important implications for the conduct of research and therapy involving embryos). If never implanted, development ceases. In the United Kingdom, regulations focus on implantation as a key to distinguishing moral status of in vitro and cloned embryos from that of an in vivo pregnancy (14). In the United States, federal regulations on fetal research apply from the time of implantation on (1).

Figure 2

Why Pursue Embryo Research?

Most contemporary discussions about embryo research center entirely on the question of the embryo's intrinsic moral status—whether or not the embryo meets specific criteria for moral personhood. Based on the understanding of the degree to which an embryo does or does not meet such criteria, these discussions have taken a stand about the permissibility of options for embryo disposition. Bioethicist Patricia King has noted that human embryo research policy should do more than reflect mere abstract assertions about the moral status of human embryos. Rather, the moral underpinnings of human embryo research should be derived from a range of values, including the facilitation of human procreation, the advancement of applied scientific knowledge, the reduction of human suffering, and the protection of vulnerable persons from coercion and exploitation (15).

There can be no compelling argument for embryo research without the promise of benefit. Potential benefits of embryo research include an improved understanding of fertilization, implantation, and early pregnancy biology and, with this understanding, possibly fewer undesired outcomes, such as miscarriage. For infertile couples, embryo research offers the possibility of more effective therapies: research efforts helped optimize conditions for intracytoplasmic sperm injection, embryo culture, and cryopreservation, for example. For others at risk for heritable genetic disease who feel pregnancy termination is undesirable or inappropriate, embryo research has led to the possibility of early, accurate genetic diagnosis: PGD provides diagnostic results at a point before implantation, so pregnancy termination can be avoided. In addition to these benefits of embryo research in general, stem cell research promises additional potential benefits, for such work may lead both to a better understanding of the processes leading to tissue differentiation and function and to possible therapies by creating lines that can replace diseased or nonfunctioning tissues. Those who donate gametes or embryos for research are offered the rewards of potentially extending scientific knowledge and, apart from any current or future hope of improving their own health, the opportunity to help others with this knowledge. Indeed, in considering the fate of excess embryos for which destruction is planned, some have argued that donation for research accords the embryo more respect than destruction alone (16, 17).

Are There Alternatives to Using Preimplantation Embryos for Research?

As with all human research, research on embryos and embryonic stem cells should be engaged in only when alternative means of developing knowledge are inadequate. Whenever possible, animal models or cell and tissue culture systems should be used to advance the understanding of human biology. However, direct extrapolation of results from in vitro animal embryo studies to humans can be misleading. Unfertilized oocytes also do not offer the same opportunities for investigating growth processes that embryos do.

Some have argued that obtaining or using embryonic stem cells is unnecessary because stem cells have been or can be isolated from umbilical cord blood or adult tissues, such as brain and skin. Yet such adult stem cells, in contrast to embryonic stem cells, have already progressed along the path of differentiation and lack the plasticity of embryonic stem cells. It is unlikely that once differentiated, these cells can be induced to form the range of tissues that can, by contrast, be produced by less-differentiated embryonic stem cells (18, 19).

Umbilical cord blood stem cells have been shown in some studies to transdifferentiate to a limited extent into nonhematopoietic cells, including those of the brain, heart, liver, pancreas, bone, and cartilage, in experimental culture and animal systems (20, 21). Some have speculated that, on the basis of these observations, cord blood might serve as a source of cells to facilitate tissue repair and regeneration in the distant future. Research is needed to clarify the role, if any, of cord blood in this field of regenerative medicine.

For those with ethical objections, recent activity in stem cell research has led to a vigorous search for alternative sources of stem cells that might obviate the need to use or destroy fresh or frozen embryos (22). Suggested techniques include 1) extraction of cells from embryos already dead, 2) nonharmful biopsy of a single blastomere from a living embryo, 3) extraction of cells from artificially created nonembryonic but embryolike cellular systems (engineered to lack the essential elements of embryogenesis but still capable of some cell division and growth), and 4) dedifferentiation of somatic cells back to pluripotency. The Committee on Ethics recognizes that such techniques, if ultimately proved to be productive, would avoid some but not all of the arguments and objections that have been raised to embryo and stem cell research. The Committee believes, however, that until such hypothetical alternatives become realities for human tissues, their possibility should not stand as a barrier to pursuing available methods of demonstrated efficacy. Indeed, technical barriers to these proposed alternatives are not trivial, and the possibility of reprogramming adult stem cells to achieve the same potential as embryonic stem cells has been termed by experts as "exceedingly rare" (23). It also is not clear that all these suggestions are free from ethical concerns or objections (eg, distinguishing when an embryo is "dead").

In considering embryonic stem cell research, it is also important to indicate why progress requires isolation of lines different from those already established. Federal regulations prohibit funding for investigations of the many new embryonic stem cell lines created since August 2001, some of which have been used by both international and U.S. researchers to advance the field. Yet, advocates of stem cell research note that in contrast to several of these newer lines, all lines on the National Institutes of Health (NIH) registry were cultured in contact with mouse cells and bovine serum, which limits potential therapeutic applications. Furthermore, the U.S. federal guidelines prohibit federal funding of somatic cell nuclear transfer techniques (also known as SCNT techniques) and research, which may offer unique opportunities for human therapy by creating cells tailored to an individual's genotype and thus, in theory, requiring less need for immunosuppression if therapeutics can one day be created from such individualized cell lines.

Are There Arguments Against Embryo Research?

Balanced against any potential benefits of embryo research are known and potential risks. Embryo research usually will involve destruction of embryos and, as a result, most human embryo research will not benefit the embryo that is used—enhancing neither its developmental potential nor its chance of survival. It is this potential harm that has led national ethics advisory committees and commissions to evaluate the moral status of the embryo and has sharply separated the two sides of the embryo research and stem cell debate. Yet, as detailed previously, this document views destruction of in vitro embryos as different from destruction of a human being.

Short of destruction, the manipulation of embryos that are intended for transfer to the uterus (as with embryo biopsy for PGD) raises concern for potential manipulation-related damage in ongoing pregnancies. Some embryo research can be validated scientifically and be beneficial clinically only if there is a subsequent transfer of the embryo to a woman's uterus in an attempt to achieve pregnancy, yet until such transfer is accomplished, it remains unknown whether research interventions will enhance or reduce the prospects for healthy life.

Women and couples who either participate in research or donate gametes or embryos for research also may be at risk. If a couple decides to donate "excess" embryos for research, such as stem cell extraction, they may be at risk for psychologic harms such as uncertainty, stress, and anxiety. These potential hazards are not exclusively related to the option of donation of embryos for research purposes and may accompany all decisions regarding the disposition of frozen embryos. When research requires hormonal stimulation and retrieval of oocytes separate from plans for pregnancy (ie, tissues obtained or created for research alone), the oocyte donor faces risks similar to those involved in oocyte donation for reproductive purposes. It is essential to ensure that a woman's or couple's choice is free of coercion and possible exploitation and that the woman or couple gives informed consent.

Recognizing such risks, some have expressed concern regarding the potential to exploit women as oocyte donors. In part to answer such concerns, some guidelines such as those proposed by the National Academy of Sciences recommend no compensation for oocyte donation for research other than for out-of-pocket expenses (24). Such restrictions, however, seem inappropriate to the ACOG Committee on Ethics and are inconsistent with policy and practice concerning compensation both to oocyte donors for reproductive purposes and women participating in other types of research protocols. Compensation for oocyte donation for reproductive purposes is supported by ASRM (25) and is customary in the United States, and there is no strong argument for distinguishing this practice from donation in the research context. The risks to the woman and the need to protect against potential abuses are similar in the two situations. Payment to an oocyte donor should be understood to be compensation for the woman's time, effort, risk, and discomfort and not as payment for the eggs that may be recovered. The level of compensation should be consistent with ASRM guidelines intended to preclude payment levels that might be construed as exerting undue influence on the donor (25). In providing advice to those seeking oocyte donors, ASRM guidelines also highlight the importance of protecting vulnerable populations and providing compensation commensurate with the time and effort involved.

Who Should Give Permission for Embryos to Be Used for Research?

Individuals will differ in their beliefs about morality of and appropriate limits for embryo research. This is true for individuals or couples creating embryos as part of infertility treatment and later making decisions regarding frozen embryos, as well as for gamete donors, who may in some cases be different from the individuals for whom the embryos were created (26, 27). In considering the question of who should give consent for research using preimplantation embryos, it is important to recognize that such research may occur long after gametes have been donated and embryos created, and in addition, the details of future research questions and protocols are unlikely to be known at the time of donation. In many cases, of course, those supplying the egg and sperm will be the same as those for whom the embryo is created, and these circumstances present the easiest conditions for obtaining appropriate, informed consent for research. In such cases, couples may indicate at the time the embryos are frozen that they would be willing to consider future donation for research, but specific permission needs to be obtained at the later time when custody is transferred to the research team. If details of the research protocol are known at the time embryos are frozen, couples should be so informed. Alternatively, some couples will be willing to donate unused embryos to an appropriate party (eg, those operating the laboratory or storage facility) for use in future research projects as yet unformulated at the time of donation. If such work includes projects in stem cell research, this should be specifically discussed and the details of stem cell research (eg, creation of immortal cell lines) described insofar as they are known at the time of donation. If both members of the couple have not previously given consent at the time custody is transferred, embryos should not be used for research.

If gamete donors are different from those for whom embryos were created, research should proceed only if gamete donors have been made aware of the option of embryo research and have given their consent to such research. Given the emotions and discussion surrounding stem cell research, potential research projects should be described as much as possible. However, gamete donors need to recognize that the details of future research projects are unlikely to be available at the time of gamete donation, and therefore donors need to be comfortable consenting to research that is described only in general terms (28). Abandoned embryos, as defined by the ASRM Ethics Committee (29, 30), should not be accepted for research.

When embryo research is conducted in anticipation of transfer (for example, PGD research), the intended parents and, if different, the gamete donors must be provided with adequate information regarding the nature of the research, the risks to the embryo, and the chances for a successful pregnancy resulting in the birth of a healthy child, and they must provide their informed consent (31). If research is to be done on an embryo that is to be transferred eventually to a third party (a gestational carrier's uterus), this individual also should give informed consent for the research.

Finally, choices should be made in circumstances free of financial or other coercion. Full information should, therefore, include assurance that consent to donation of embryos for research is not a condition for receiving services and that fee scales are not contingent on consent to research. Moreover, donors of embryos should understand that they will receive no compensation for their donation of excess embryos. The consent process also should cover any possible identifiers that will be maintained with the tissue to link it back to the donors, access to current and future health information from donors, willingness of donors to be contacted in the future, ownership, patent rights, and commercial uses of stem cell lines that may be developed from the embryo. All providing consent also should understand that they may withdraw their consent up to the time that the donated tissues actually are used in research.

In the scenarios of adults donating gametes for the creation of embryos solely for research and adults donating somatic cells for somatic cell nuclear transfer, special considerations must be taken into account. The information provided to donors for embryonic stem cell research must acknowledge that the process of obtaining the embryonic stem cell line from the inner cell mass of the blastocyst will result in the destruction of the embryo and also should indicate that the derived stem cell lines may be propagated indefinitely. The consent process also should cover the same elements as consent obtained when unused embryos are donated for research. A woman wishing to donate oocytes for research must be informed of possible risks to her in the process of controlled ovarian hyperstimulation and retrieving oocytes, and egg donor programs should set up medical and psychologic screening procedures in order to safeguard potential donors.

May Embryos Be Created for Research?

Many cryopreserved embryos exist in the United States. When such embryos are appropriate to the questions under investigation and appropriate consent can be obtained, the ACOG Committee on Ethics recommends that these embryos be the preferred resource for research. Not all frozen embryos are available or appropriate for research, however, and frozen embryos may not meet all criteria necessary for some therapeutic applications (32). Investigations of specific genetic defects, for example, may require specific tissues not available in already frozen embryos, and any future therapies using stem cells (eg, somatic cell nuclear transfer) by design may require that embryos and the derived embryonic stem cells have a genetic profile identical to the intended recipient. The Committee on Ethics believes that the promise of somatic cell nuclear transfer as a technique to create important and unique stem cell lines is such that research in this area is justified, a finding consistent with the practices of the United Kingdom's Human Fertilisation and Embryology Authority (33). Furthermore, the Committee on Ethics can imagine a future day when the creation of tissues via somatic cell nuclear transfer to be used in the isolation of human stem cell lines for therapeutic purposes will be possible and needed; if so, the Committee on Ethics would consider this process to be ethically appropriate.

Although there are no physical differences between "excess" embryos from an IVF therapy and "created-for-research" embryos, the moral distinction that many make seems to rest on the intent of the creation of the embryo, whether for procreation or research, and the special respect given to human embryos. An embryo originally created for procreation may be seen to be created for its own sake, as an "end in itself," whereas an embryo created for research may appear to be a "mere means" to the ends of others. For some, the respect given to the human embryo differentiates the embryo from mere human tissues or cells and necessitates greater obligation to justify valid scientific inquiry. Others judge that the potential benefits of research for societal health outweigh any limitations conferred by the respect due to human embryos, whether they are "excess" embryos or "created for research."

There is a precedent for creation of embryos for research purposes. The early work in human IVF by Edwards and colleagues consisted of fertilizing human oocytes for research in order to study the normality of the zygotes thus created before transfer to a woman was even considered (34). In 1994, the NIH Human Embryo Research Panel approved the creation of IVF embryos for research when the very nature of the research itself required the fertilization of oocytes and when a research project deemed to be exceptionally important required a particular type of embryo for its validity. Currently, there is little need for the creation of embryos by fertilization for research purposes, but in the future the supply of available tissues, research questions, or therapeutic paradigms may change. If a compelling need arises, the question of creating embryos by fertilization for use in research will need to be addressed carefully.

Does Experimental or Other Use of Stem Cells Lend Support to Reproductive Cloning?

In the processes involved, associated risks, and intended outcomes, work involving stem cells and cloning for biomedical research with the intent of developing future therapies (eg, somatic cell nuclear transfer) may clearly be distinguished from reproductive cloning. The former areas of research and practice involve the isolation and manipulation of cells from embryos that are not allowed to progress past the 14-day stage and are not transferred to the uterus. Because reproductive cloning is designed to produce a human being, it raises a distinct set of issues and concerns, and these are not the focus of this Committee Opinion. The support expressed in this Committee Opinion for embryo research and cloning for research purposes does not imply endorsement of reproductive cloning, which the Committee on Ethics opposes.


The Committee on Ethics takes the position that human embryo research can be justified under certain conditions. This position is based on an interpretation of the moral status of the embryo as a living entity with a human genetic code, deserving of some form of respect in itself and not solely for its usefulness in research. But this position also recognizes the value of the embryo as relative, in the sense that it does not require the degree of protection and absolute respect that is accorded human persons. In other words, the embryo is human—not simply like other human tissue (for it is genetically unique and has human potential)—but it also is not a human person.

Risks of harm to the embryo in research can be justified, but not without limits. Embryos, for example, should not be subjected to trivial or poorly designed research programs; if the embryos are designated for transfer to a woman's uterus, the goals of successful pregnancy should be given priority; and the real and symbolic values of the embryo should not be negated or trivialized. The Committee on Ethics recommends the following guidelines for clinical and laboratory research involving human embryos.

  1. Research will be conducted only by scientifically qualified individuals and in settings that include appropriate and adequate resources and protections. The design of the research and each of its procedures should be clearly formulated in a research protocol that is submitted to a specially appointed independent committee for evaluation, guidance, and approval.
  2. The question to be explored must be scientifically valid; must take into account scientific work to date, including animal studies; and cannot be answered through research on animal embryos or on unfertilized gametes.
  3. The information sought should offer potential scientific and clinical benefit in areas such as embryonic development, human reproduction, chromosomal and genetic conditions, or, for embryonic stem cell lines, potential disease therapies.
  4. The research will be conducted using embryos at the earliest possible developmental stage of the embryo, not to exceed 14 days after evidence of fertilization in any case.
  5. Any embryo that has undergone research will be transferred to a uterus only if the original research was undertaken to prepare the embryo for selection or placement or to improve its chances for implantation and only if specific consent for transfer is obtained.
  6. Intended parents for whom embryos are created (embryo donors) should be provided with the opportunity to provide informed consent as to the disposition of any excess embryos, whether for eventual destruction, donation for attempted implantation by another individual or couple, or scientific research. This presupposes an explicit policy on the part of the researchers and their sponsoring institutions that facilitates communication of options and provides for informed donor choice. If gamete donors differ from the embryo donors, then embryos may be donated for research only if the gamete donors also have given explicit consent for donation for research.
  7. Those donating "excess" frozen embryos for embryonic stem cell research must be adequately informed of the goals, anticipated benefits, and potential hazards of the particular research. Each potential donor is informed that she or he is at liberty to decline participation in the research and, until such a point when the tissues are used or cell lines created, to withdraw consent for research.
  8. Other information must be included in informed consent for donation of embryos for stem cell research:
    • Acknowledgment that removal of the inner cell mass will destroy the embryo
    • Statement that stem cell lines may continue indefinitely and be shared with other researchers
    • Discussion of potential ownership, patent, and commercial uses of stem cell lines that may be developed from the embryo
    • Information regarding whether any identifiers will be preserved in the stem cell lines derived
  9. For research or therapy involving somatic cell nuclear transfer, oocyte donors and somatic cell donors must give informed consent for use of their eggs or somatic cells. In the rare circumstances in which IVF embryos are created for research, the gamete donors should provide informed consent for fertilization for research purposes. In both cases, informed consent should include points in guideline 8 and clearly describe the researchers' intention to deliberately create a human embryo for research.
  10. Special care must be taken to ensure that potential donors of oocytes for research understand the procedure and its risks. To safeguard donors as much as possible, medical and psychologic screening should be required. Although compensation for egg donors for research is acceptable, as it is for donors for infertility treatment, such compensation should be understood to be compensation for the woman's time, effort, risk, and discomfort and not as payment for the eggs that may be recovered. The level of compensation should be consistent with ASRM guidelines to minimize the possibility of exploitation of egg donors.
  11. Techniques and research designed to clone human beings raise a different set of ethical concerns. The Committee on Ethics opposes reproductive cloning.


The Committee on Ethics has offered a position that supports embryo research but limits it according to ethical guidelines. This position advocates treatment of the embryo with respect but not the same level of respect that is given to human persons. It is a position that will not be acceptable to those who believe that full rights should be extended to early-stage embryos. In arriving at its position, the Committee on Ethics considered scientific and clinical information relevant to ethical analysis, although it recognizes that such consideration necessarily involves both scientific and ethical interpretation of what cannot be simply incontrovertible "facts."

The Committee on Ethics once again acknowledges that no single position can encompass the variety of opinions within the membership of ACOG, and it affirms that no physician should be required or expected to participate in embryo research if he or she finds it morally objectionable. Nonetheless, it is important to public discourse and to the practice of responsible medicine that physicians become aware of the medical and ethical issues involved in the complex areas of embryo research. To advance this discourse, it is helpful for physicians to reflect on and share the basis of their own views and to recognize and explore the ethical perspectives of their patients and colleagues.


  1. Definitions. 45 CFR § 46.202 (2005).
  2. U.S. Department of Health, Education, and Welfare. HEW support of research involving human in vitro fertilization and embryo transfer. Washington, DC: U.S. Government Printing Office; 1979.
  3. Ethical considerations of the new reproductive technologies. Ethics Committee of the American Fertility Society. Fertil Steril 1986;46(suppl 1):1S–94S.
  4. Ethical considerations of the new reproductive technologies. Ethics Committee of The American Fertility Society. Fertil Steril 1990;53(suppl 2):1S–104S.
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*Blastocyst: A preimplantation embryo of approximately 150 cells. The blastocyst consists of a sphere made up of an outer layer of cells (the trophectoderm), a fluid-filled cavity (the blastocoel), and a cluster of cells on the interior (the inner cell mass).

Blastomere: The cells derived from the first and subsequent cell divisions of the zygote.

*Embryo: In humans, the developing organism from the time of fertilization until the end of the eighth week of gestation, when it becomes known as a fetus. Other ACOG guidelines address research involving postimplantation embryos and fetuses (ie, research during pregnancy). (American College of Obstetricians and Gynecologists. Research involving women. In: Ethics in obstetrics and gynecology. 2nd ed. Washington, DC: ACOG; 2004. p. 86–91.)

*Embryonic stem cells: Primitive (undifferentiated) cells from the embryo that have the potential to become a wide variety of specialized cell types.

Fertilization: The process whereby male and female gametes unite.

Gametes: Mature reproductive cells, usually having half the adult chromosome number (ie, sperm or ovum).

Implantation: Attachment of the blastocyst to the endometrial lining of the uterus and subsequent embedding in the endometrium. Implantation begins approximately 5–7 days after fertilization and may be complete as early as 8–9 days after fertilization.

*Inner cell mass: The cluster of cells inside the blastocyst. These cells give rise to the embryonic disk of the later embryo and, ultimately, the fetus.

Oocyte: An immature female reproductive cell, one that has not completed the maturing process to form an ovum (gamete).

Pluripotent: Able to differentiate into multiple cell and tissue types.

Preimplantation embryo: In humans, the developing organism from the time of fertilization until implantation in the uterus or other tissue (eg, ectopic pregnancy).

Primitive streak: The initial band of cells from which many tissue systems, including the neural system of the embryo, begin to develop, located at the caudal end of the embryonic disc. The primitive streak is present approximately 15 days after fertilization and marks the axis along which the spinal cord develops.

Somatic cell nuclear transfer: The transfer of a cell nucleus from a somatic cell into an egg from which the nucleus has been removed.

Stem cells: Undifferentiated multipotent precursor cells that are capable of perpetuating themselves indefinitely and of differentiating into specialized types of cells.

Totipotent: Able to differentiate into every cell and tissue type; the capacity of a cell or group of cells to produce all of the products of conception: the extra-embryonic membrane and tissue, the embryo, and, subsequently, the fetus.

Zygote: The single cell formed by the union of the male and female haploid gametes at syngamy.

*Definitions marked with an asterisk are adapted from the National Institutes of Health glossary, available at:

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Using preimplantation embryos for research. ACOG Committee Opinion No. 347. American College of Obstetricians and Gynecologists. Obstet Gynecol 2006;108:1305–17.

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