Most stem cells used in medical treatments and research do not come from aborted fetuses. The confusion stems from the fact that “stem cells” is a broad term covering several distinct cell types, each with a different source. Embryonic stem cells come from leftover IVF embryos, not abortions. The stem cells used in approved therapies today come from adult bone marrow, fat tissue, or umbilical cord blood collected after a normal delivery. There is, however, a separate category of fetal tissue research that has used cells from elective abortions, and understanding the differences between all of these clears up a persistent and widespread misconception.
Where Embryonic Stem Cells Actually Come From
Human embryonic stem cells are derived from blastocysts, which are clusters of roughly 100 to 200 cells that form about five days after fertilization. These blastocysts come from in vitro fertilization (IVF) clinics. When couples undergo IVF, the process typically produces more embryos than are needed. The surplus embryos are frozen, and some are eventually donated for research with written informed consent from the donors.
A landmark study published in the New England Journal of Medicine described the standard process: researchers obtained frozen embryos produced by IVF for clinical purposes, cultured them to the blastocyst stage, and then isolated the inner cell mass, which is the cluster of cells capable of becoming any tissue in the body. At no point in this process is an abortion involved. The embryos are microscopic, never implanted in a uterus, and would otherwise remain frozen indefinitely or be discarded.
Federal law in the United States, through the Dickey Amendment, prohibits NIH funding from being used to create or destroy human embryos for research. Researchers can only work with stem cell lines that were derived under strict ethical guidelines, including confirmation that donors received no payment and gave voluntary consent without restrictions.
Fetal Tissue Research Is a Separate Category
There is a distinct area of biomedical research that has used tissue from elective abortions, but this is not the same as embryonic stem cell research. Fetal tissue research involves cells collected from terminated pregnancies, typically with consent from the patient, and has contributed to major medical advances over the past several decades.
The most significant contributions involve cell lines created in the 1960s and 1970s. Two cell lines in particular, known as WI-38 and MRC-5, were derived from fetal lung tissue and became essential tools for vaccine production. The rubella vaccine is still manufactured using WI-38 because it is safer and more effective than versions developed with non-human cells. The chickenpox virus does not grow well in non-human cells, making fetal cell lines necessary for that vaccine as well. Hepatitis A vaccines are also produced using these lines.
More recently, fetal-derived cell lines played a role in COVID-19 vaccine development. The AstraZeneca and Johnson & Johnson vaccines were manufactured using cell lines (HEK293 and PER.C6) originally derived from fetal tissue decades ago. HEK293 was created in 1977 from embryonic kidney cells, while PER.C6 was established in 1998 from embryonic retinal cells. These are not fresh tissue from ongoing abortions. They are laboratory cell lines that have been reproducing in culture for decades, many generations removed from the original cells.
Fetal tissue has also been critical for HIV research. Mice engrafted with human fetal bone marrow, liver, and thymus tissue have allowed scientists to study how the virus spreads and to test treatments based on neutralizing antibodies.
What Approved Stem Cell Therapies Actually Use
The stem cells used in current medical treatments come from the patient’s own body or from donors after birth. Bone marrow is considered the gold standard source and remains the only stem cell material the FDA has fully approved for therapeutic use (primarily for blood cancers and immune disorders). Adipose tissue, or body fat, is the other major clinical source. Both are collected from living adults through minimally invasive procedures.
Umbilical cord blood is another established source. It is collected from the umbilical cord and placenta immediately after a healthy delivery. The mother and baby are unaffected. Cord blood stem cells have been successfully used to treat graft-versus-host disease and autoimmune conditions like lupus.
Private stem cell clinics that market treatments for joint pain, aging, or cosmetic purposes typically use cells derived from umbilical cords or amniotic membranes, both collected after normal deliveries. These are not sourced from abortions or embryos.
How Scientists Bypass Embryos Entirely
In 2006, Japanese researcher Shinya Yamanaka demonstrated that ordinary adult skin cells could be reprogrammed back into a stem cell state by introducing four specific proteins. These reprogrammed cells, called induced pluripotent stem cells (iPSCs), behave almost identically to embryonic stem cells: they can become virtually any cell type in the body.
The process works by activating genes that are normally only active in embryonic development, effectively resetting the cell’s identity. Since then, researchers have successfully reprogrammed skin cells, blood cells, and other adult tissues into pluripotent stem cells. This technology has largely reduced the need for embryonic stem cells in many research applications, because scientists can now generate patient-specific stem cells from a simple blood draw or skin biopsy.
Why the Confusion Persists
Several factors keep this misconception alive. The word “embryonic” in embryonic stem cells leads people to assume a pregnancy was involved, when in reality the embryos never left a lab dish. The existence of genuine fetal tissue research, which does have a historical connection to abortion, gets conflated with stem cell therapy in general. And political debates have often grouped these very different categories together under a single umbrella.
The distinction matters practically. Embryonic stem cells come from unused IVF embryos. Fetal tissue and fetal cell lines have a historical link to elective abortions, but the cell lines used today were established decades ago and are many generations removed from the original tissue. Adult stem cells and cord blood come from living people. And iPSCs come from reprogrammed adult cells with no embryo involved at all. Each of these has a different source, a different ethical profile, and a different role in medicine.