Two women can already share a biological role in having a baby through reciprocal IVF, a procedure in which one partner provides the egg and the other carries the pregnancy. That child is genetically related to one mother and gestationally related to the other. A child genetically related to both mothers, however, remains in the realm of experimental science, though recent breakthroughs in stem cell biology and gene editing have moved this possibility closer to reality than most people realize.
Reciprocal IVF and How It Works Today
The most established route for two women to share biological motherhood is reciprocal IVF, sometimes called the ROPA method (Reception of Oocytes from PArtner). One partner undergoes ovarian stimulation and egg retrieval. Those eggs are fertilized in a lab with donor sperm, and the resulting embryo is transferred into the other partner’s uterus. The woman who provided the egg is the genetic mother; the woman who carries the pregnancy is the gestational mother.1PubMed Central. Lesbian shared IVF: the ROPA method: a systematic review This is the only assisted reproduction technique currently used in clinics that lets both women in a couple contribute biologically to the same pregnancy.2Family Relations. “Her bun in my oven”: Motivations and experiences of two‐mother families who have used reciprocal IVF
A related approach called intravaginal culture (IVC) also allows shared conception, though it is less widely available. In IVC, the egg and sperm are placed in a small capsule that sits inside one partner’s vagina during the early fertilization period, before the embryo is transferred to the other partner. Both reciprocal IVF and IVC require donor sperm, which means the resulting child carries DNA from the egg-providing mother and from the sperm donor, not from both women.3PubMed Central. A systematic review of reproductive technologies for shared conception in same-sex female couples
For many couples, that shared physical involvement is deeply meaningful even without a full genetic connection to both parents. Research into the motivations of two-mother families who chose reciprocal IVF consistently finds that the desire to feel equally invested in the pregnancy, and equally recognized as parents, drives the decision.2Family Relations. “Her bun in my oven”: Motivations and experiences of two‐mother families who have used reciprocal IVF But the question most people are really asking when they search this topic is something bigger: could a baby ever carry the genes of two women, with no male genetic contribution at all?
Why Two Eggs Cannot Simply Be Combined
In ordinary mammalian reproduction, a sperm cell does more than deliver half a genome. The sperm contributes structures called centrioles, which the fertilized egg needs to organize its first cell divisions. The egg’s own centriole-building apparatus has been largely dismantled during its development, so it relies on the sperm’s centrioles as templates to restart the process.4PubMed. Loss and Rebirth of the Animal Microtubule Organizing Center: How Maternal Expression of Centrosomal Proteins Cooperates with the Sperm Centriole in Zygotic Centrosome Reformation Fusing two eggs together would leave the resulting cell without these templates, stalling development very early.
There is also a deeper genetic obstacle called genomic imprinting. Mammals silence certain genes differently depending on whether they were inherited from the mother or father. Some genes are active only on the copy from Dad; others only on the copy from Mom. An embryo made from two eggs would receive two maternally imprinted copies of every gene and zero paternally imprinted ones. The resulting imbalance is lethal in mammals under natural conditions, causing severe placental and growth defects that halt development. Overcoming imprinting is the central technical challenge for any future technology that aims to produce a baby genetically related to two women.
Bimaternal Mice and the Imprinting Problem
In 2018, a Chinese research team demonstrated that the imprinting barrier could be overcome in mice. They used gene editing to delete three specific imprinted regions in embryonic stem cells derived from a single female mouse, then injected those modified cells into eggs from a second female mouse. The result was 29 live pups out of 210 transferred embryos, roughly a 14 percent success rate, comparable to the efficiency of standard assisted reproduction using sperm.5Cell Stem Cell. Generation of Bimaternal and Bipaternal Mice from Differentially Methylated Haploid Embryonic Stem Cells – Section: Results
The bimaternal mice were not just alive; they were healthy. Their body and placenta weights were normal, their behavior tracked with typical mice, and a genome-wide analysis showed that all detected imprinted genes were expressed normally despite the unusual parentage.5Cell Stem Cell. Generation of Bimaternal and Bipaternal Mice from Differentially Methylated Haploid Embryonic Stem Cells – Section: Results These mice grew to adulthood and were fertile. When bred with normal males, they produced litters of normal size, around seven pups per litter, matching the reproductive output of ordinary female mice.6Cell Stem Cell. Generation of Live Bimaternal and Bipaternal Mice from Uniparental Haploid Embryos and Imprinted Region-Deleted Haploid ESCs – Section: Results
A separate earlier study on bimaternal mice found something unexpected about their lifespan. Mice created from two mothers, with carefully corrected imprinting, survived on average 186 days longer than conventionally produced controls. They also weighed less in old age.7Oxford Academic (Human Reproduction). Longevity in mice without a father That is an intriguing finding, though researchers are cautious about reading too much into it. Mouse lifespans are short, their genetics are tightly controlled in lab settings, and the mechanisms behind the longevity difference remain unclear.
The bimaternal mouse experiments are proof-of-concept that two-mother offspring are possible in mammals. But moving from mice to humans means confronting a genome that is far more complex, with more imprinted genes, more regulatory layers, and much higher stakes if something goes wrong.
In Vitro Gametogenesis and Lab-Grown Eggs and Sperm
The technology most likely to eventually let two women have a fully genetic child is called in vitro gametogenesis, or IVG. The idea is to take an ordinary body cell from one partner, reprogram it into a stem cell, and then coax that stem cell into becoming a sperm cell or an egg. If you could make functional sperm from a woman’s skin cell, you could fertilize her partner’s egg with it, producing an embryo genetically related to both women.
Researchers have already demonstrated key steps of this process. Pluripotent stem cells, including both embryonic stem cells and induced pluripotent stem cells made from adult tissue, have been successfully guided into becoming primordial germ-cell-like cells, the precursors to eggs and sperm.8PubMed Central. Making gametes from pluripotent stem cells: embryonic stem cells or very small embryonic-like stem cells? In mice, this process has been pushed far enough to produce functional eggs and sperm-like cells that resulted in live offspring. In humans, the process has stalled at earlier stages, and no functional human egg or sperm cell has been produced from stem cells in a lab to date.
One particularly tricky piece of the puzzle is epigenetic reprogramming. Eggs and sperm carry distinctive chemical tags on their DNA, methylation marks that tell genes when to turn on and off. These marks are established during germ cell development and are critical for normal embryo development. In 2024, researchers reported successfully erasing and rewriting these methylation marks in human cells, guiding them toward sperm-like or egg-like epigenetic states.9PubMed. Lab-grown sperm and eggs: ‘epigenetic’ reset in human cells paves the way That work has not yet produced a finished gamete, but it clears a hurdle that many scientists had considered among the hardest to solve.
There is an additional chromosome challenge specific to making sperm from female cells. Women carry two X chromosomes and no Y chromosome. A sperm cell normally carries either an X or a Y. To make functional sperm from a woman’s cells, you would need to either engineer a Y chromosome’s essential functions into the cell or find a way to produce sperm without one. Mouse research has shown that the vast majority of the Y chromosome is dispensable for producing offspring: only two Y-linked genes were needed to drive the creation of haploid germ cells that could generate live pups through assisted reproduction.10PubMed Central. Two Y genes can replace the entire Y chromosome for assisted reproduction in the mouse Whether those genes could be synthetically introduced into female-derived cells and still function correctly in humans is an open question, but the finding narrows the gap considerably.
If IVG ever works with female-derived sperm, every child of two women would carry two X chromosomes and therefore be female. No Y chromosome exists in either parent’s genome, so there is no way to produce a male child from two biological mothers alone.
Polar Body Transfer and Other Experimental Approaches
Another line of research worth knowing about involves polar bodies, the tiny cells that are cast off when an egg undergoes its final cell divisions. Polar bodies contain a full copy of the mother’s nuclear DNA but are normally discarded. Researchers have demonstrated that a polar body genome can be transferred into an enucleated donor egg to produce a functional oocyte. In human experiments, these reconstructed eggs supported normal fertilization with sperm and developed into blastocysts, though at a lower rate than untreated eggs (about 42 percent versus 75 percent for controls).11Cell Stem Cell / PubMed Central. Functional Human Oocytes Generated by Transfer of Polar Body Genomes
Polar body transfer was developed primarily as a way to prevent mitochondrial disease, not to enable same-sex reproduction. Mitochondria, the energy-producing structures in cells, carry their own small DNA, and that DNA is inherited exclusively from the mother. Women who carry mitochondrial mutations can pass them to every child. By moving only the nuclear DNA into a donor egg with healthy mitochondria, the technique could prevent disease transmission.12Europe PMC. Three-parent in vitro fertilization: gene replacement for the prevention of inherited mitochondrial diseases In theory, a modified version of this technology could be combined with IVG techniques to allow one woman’s nuclear DNA to be placed into another woman’s egg cytoplasm, though that application remains speculative and has not been attempted.
How Far Away Is This for Humans
The honest answer is that nobody knows with certainty, but most researchers working in the field describe a timeline of decades rather than years for a clinically safe version of IVG-based same-sex reproduction. The gap between mouse proof-of-concept and human clinical use is enormous. Mice develop in about three weeks and have short generation times, making it feasible to track health outcomes across multiple generations quickly. Human pregnancies take nine months, and meaningful safety data would require following children for years or decades.
Several technical problems remain unsolved in humans. The stem-cell-to-gamete process is inefficient even in mice. The imprinting edits required to produce healthy bimaternal mice involved precise deletions at three genomic sites, and the human genome has more imprinted regions, many of which are not as well characterized. Off-target effects of gene editing remain a concern, though the precision of CRISPR tools is improving rapidly. And even if functional human gametes could be produced, no regulatory body in the world currently permits their use in creating embryos intended for pregnancy.
Some observers have noted that specific applications of IVG could move faster. Stem-cell-derived eggs for women who have lost ovarian function, using their own cells to make new eggs rather than cross-sex gametes, face fewer biological hurdles and may reach clinical trials sooner.13PubMed Central. Stem cells as new agents for the treatment of infertility: current and future perspectives and challenges That same infrastructure and knowledge base would eventually feed into the more complex challenge of making sperm from female cells.
Legal Barriers and Insurance Access
Even for the assisted reproduction options available today, the legal landscape creates significant obstacles for same-sex female couples. In many jurisdictions, the legal definition of infertility was written with heterosexual couples in mind, requiring months or years of documented failed attempts at conception before insurance will cover IVF. For a same-sex female couple, those failed attempts with a male partner obviously do not apply, and many were forced into unnecessary rounds of intrauterine insemination with donor sperm before they could access IVF coverage.
New York State addressed this in 2021 by eliminating the requirement that same-sex female couples undergo up to 12 months of intrauterine insemination before qualifying for IVF coverage. The impact was immediate and dramatic: the median time from initial consultation to starting IVF dropped from 297 days to 173 days, and the proportion of couples beginning treatment within a year of their first appointment rose from 57 percent to 86 percent.14PubMed. Breaking Down Barriers for Same-Sex Female Couples Building Families: In Vitro Fertilization Utilization Following the Enactment of 2021 Legislation in New York State Couples in the post-legislation group also reached an ongoing pregnancy faster, with a median time from consultation to discharge with a pregnancy of 383 days compared to 535 days before the law changed.
For reciprocal IVF specifically, cost-effectiveness data remain limited, and the procedure’s extra complexity compared to standard IVF raises both expense and unresolved practical questions about insurance classification.15PubMed. IVF with reception of oocytes from partner in lesbian couples: a systematic review and SWOT analysis In countries without public fertility coverage, the out-of-pocket cost of reciprocal IVF can be substantially higher than a single round of standard IVF, since two women undergo medical procedures rather than one.
Looking further ahead, the legal questions surrounding IVG-derived gametes are even murkier. German legal scholars have pointed out that if artificial gametes become possible, same-sex couples could have genetically related children, but so could a single individual, by deriving both egg and sperm from their own cells. Existing reproductive laws in most countries were not written to address either scenario.16Bioethics. Framing the ethical and legal issues of human artificial gametes in research, therapy, and assisted reproduction: A German perspective Most jurisdictions ban the clinical use of lab-derived gametes outright or have no framework to regulate them, which means the legal infrastructure would need to be built alongside the science.
Ethical Questions That IVG Raises
The prospect of making eggs or sperm from stem cells opens a wider ethical conversation than just same-sex reproduction. One concern is safety: any child born through IVG would be the product of a technology with no long-term track record, and there is no way to obtain informed consent from the person most affected, the future child. The bimaternal mice appeared healthy and fertile, but mice are not humans, and subtle developmental differences could manifest as health problems years after birth.
There are also questions about reproductive autonomy and access. If IVG becomes clinically available, who should be able to use it? Infertile heterosexual couples? Same-sex couples? Postmenopausal women? Single individuals who want a child genetically related only to themselves? A survey of the Belgian public found broadly positive attitudes toward IVG and its applications, with one exception: respondents were uncomfortable with using IVG for postmenopausal women. They also expressed mixed feelings about the animal and embryo experimentation necessary to develop the technology.17Reproductive Biomedicine & Society Online. Enthusiasm, concern and ambivalence in the Belgian public’s attitude towards in-vitro gametogenesis
Ethicists have also flagged the tension between the technology’s promise and its potential misuse. Stem-cell-derived gametes could eliminate the need for egg donors, which would reduce the physical risks currently borne by women who undergo ovarian stimulation for donation. But they could also enable forms of reproduction that most societies have not yet decided whether to permit, like creating a child from a deceased person’s stored cells or from cells obtained without someone’s knowledge or consent.18Springer Link / Annals of Biomedical Engineering. Balancing Ethical Pros and Cons of Stem Cell Derived Gametes
Public Attitudes Toward Same-Sex Couples Using Reproductive Technology
Public comfort with assisted reproduction varies widely depending on who is using it. Research examining attitudes across populations has consistently found that people who are generally supportive of IVF and donor insemination for heterosexual couples are often supportive for same-sex couples as well, though comfort levels tend to be slightly lower for same-sex scenarios. One study identified a distinct group of respondents who were comfortable with heterosexual couples using all forms of assisted reproduction, including surrogacy, but opposed any use of reproductive technology by gay or lesbian couples.19Gay & Lesbian Issues and Psychology Review. Comfort With Use of Assisted Reproductive Technologies (Art) for Family Formation by Same-Sex and Heterosexual Couples – Section: Results
A systematic review of stakeholder views on artificial gametes noted that the prospect of same-sex couples conceiving genetically related children was one of the most frequently discussed potential applications, alongside its use for infertile heterosexual couples and postmenopausal women.20Human Reproduction Update. Potential consequences of clinical application of artificial gametes: a systematic review of stakeholder views The conversation around IVG is moving faster in bioethics journals than in public policy, and the gap between what science can do and what law and social consensus permit will likely widen before it narrows.
What the Gestational Mother Contributes Beyond Genetics
One detail often overlooked in conversations about biological parenthood is that the gestational mother contributes more than a womb. During pregnancy, the fetal and maternal environments influence each other in lasting ways. The gestational mother’s immune system shapes the fetus’s developing immune responses. Her microbiome colonizes the baby during birth. Epigenetic changes driven by nutrition, stress levels, and other environmental factors during pregnancy can alter gene expression in the child for years. In reciprocal IVF, where one mother provides the egg and the other carries the pregnancy, both women leave a biological mark on the child, even though only one contributes nuclear DNA.
Mitochondrial DNA adds another layer. In standard reciprocal IVF, the child’s mitochondria come from the egg provider, not the gestational carrier. But techniques like mitochondrial replacement therapy, originally designed to prevent inherited mitochondrial disease, demonstrate that it is technically possible to separate nuclear DNA from mitochondrial DNA and recombine them from different sources.12Europe PMC. Three-parent in vitro fertilization: gene replacement for the prevention of inherited mitochondrial diseases In a speculative future where IVG and mitochondrial transfer were both available, one could imagine a child carrying nuclear DNA from both mothers and mitochondrial DNA from one of them or even from a donor, adding yet another dimension to what “biological parenthood” means.
The definition of a biological parent, in short, is already more complicated than the simple question of whose DNA the baby carries. For two-mother families today, the gestational relationship is a genuine biological connection, and the science increasingly supports treating it as one. For two-mother families in the future, the genetic connection may become possible too, though the timeline and safety hurdles ensure that day is still a long way off.