Could an Experimental IVF Technique Expand Future Fertility Options?
New sheep research explores whether highly immature ovarian follicles can be grown into mature eggs, with potential implications for future fertility preservation.
Incremental Science, Real Patient Questions
Fertility science often moves forward through careful, incremental research. A recent experiment involving sheep has drawn attention because researchers were able to grow eggs from very early-stage ovarian follicles in the laboratory, use those eggs in IVF, and produce healthy offspring.
The findings are promising, particularly for the future of fertility preservation. They are also early. This approach has not been tested as a fertility treatment in humans, is not available in clinics, and will require much more research before scientists can know whether it is safe or effective for patients.
What Did the Researchers Accomplish?
The July 2026 Yahoo report on lambs born through an experimental IVF technique described five sheep born after researchers coaxed highly immature eggs to mature in the laboratory. According to the report, one of those sheep later produced two offspring of its own, offering an early sign that the resulting animal was fertile.
The study focused on eggs held within preantral follicles. These follicles are at an earlier stage than the larger follicles normally targeted during a standard IVF retrieval. Instead of waiting for the follicles to mature inside the ovary, the researchers isolated them and supported their growth through several laboratory stages before attempting fertilization.
In the 2026 Human Reproduction study abstract on in-vitro-grown sheep oocytes, the University of Leeds-led team reported studying 2,780 early preantral sheep follicles. The follicles were grown in the laboratory for 17 to 27 days, followed by additional steps for hormone production, egg maturation, IVF, and embryo culture.
This is better described as complete in vitro growth and maturation, or IVGM, rather than conventional IVF alone. IVF refers to fertilizing eggs outside the body. IVGM adds a much earlier laboratory phase intended to help an immature follicle and its egg develop far enough to become capable of fertilization.
How Is This Different From Standard IVF?
During a typical menstrual cycle, a group of follicles begins developing, but usually one becomes dominant and releases an egg at ovulation. In a standard IVF cycle, hormone medications encourage multiple follicles to mature at the same time. A fertility specialist then retrieves eggs from those developed follicles.
Even with stimulation, not every follicle produces an egg, not every retrieved egg is mature, and not every mature egg fertilizes or becomes an embryo. The number of eggs available is influenced by factors such as age, ovarian reserve, diagnosis, and the body’s response to medication.
The experimental technique starts earlier. Researchers work with small, immature follicles taken from ovarian tissue and try to reproduce the signals those follicles would normally receive as they grow inside the ovary. If that process could eventually be adapted safely for humans, it might make use of follicles that conventional egg retrieval cannot access.
That does not mean patients could simply add this technique to a regular IVF cycle to produce many more eggs. Obtaining early follicles requires ovarian tissue, and the research team noted that this is more invasive than collecting mature eggs during a conventional retrieval. Any future clinical use would need to show that its potential benefits outweigh the surgical, laboratory, and medical risks.
Why This Research May Matter for Cancer-Related Fertility Preservation
Some chemotherapy, radiation, and surgical treatments can damage ovarian function. When time and medical circumstances allow, patients may be able to freeze eggs or embryos before treatment. Ovarian tissue cryopreservation is another established option in selected situations, including for some patients who cannot delay treatment or who have not gone through puberty.
Ovarian tissue cryopreservation typically involves removing and freezing ovarian tissue that contains many immature follicles. The tissue may later be transplanted back into the body in an effort to restore fertility. For certain cancers, however, clinicians must consider whether transplanted tissue could reintroduce malignant cells.
IVGM is being studied as a possible way to use follicles from ovarian tissue without transplanting the tissue itself. Scientists would instead attempt to grow and mature the eggs entirely in the laboratory before fertilization. That possibility is why the researchers describe the work as especially relevant to oncofertility patients who may face a risk of reseeding cancer through tissue transplantation.
This remains a future possibility, not a current alternative that patients can choose today. Anyone preparing for potentially fertility-damaging treatment needs individualized counseling from both an oncology team and a reproductive specialist. Our overview of what oncofertility care includes explains how those specialties can work together.
What the Results Do and Do Not Show
The study offers an important proof of concept: eggs grown from early sheep follicles completed maturation, were fertilized, formed embryos, and produced healthy offspring. Sheep are valuable for this stage of research because aspects of their ovarian and reproductive biology are more similar to humans than those of mice.
Still, success in sheep does not establish that the method will work in people. The underlying study reported a mature-egg rate of about 36 percent, and only a small number of follicles and eggs completed every step through blastocyst development and embryo transfer. The researchers themselves called for larger follow-up studies.
Before any human clinical use, scientists would need to investigate questions including:
- Whether human follicles can be grown reliably through the full process
- Whether the resulting eggs and embryos are chromosomally and developmentally healthy
- Whether laboratory conditions affect gene activity or long-term health
- Which patients, if any, might benefit enough to justify ovarian tissue collection
- How outcomes compare with established fertility-preservation options
- What ethical and regulatory safeguards would be required
These are not small details. Fertility technology should be judged by healthy outcomes and long-term safety, not simply by whether it can produce more mature eggs in a laboratory.
Could It Improve IVF Success Rates?
Possibly, but that has not been demonstrated in humans. Having access to more mature eggs could theoretically create more opportunities for fertilization and embryo development. Yet more eggs do not automatically mean more healthy embryos, successful pregnancies, or live births.
IVF outcomes depend on many connected factors, including egg and sperm health, embryo development, uterine conditions, laboratory quality, age, and the reason treatment is needed. A future IVGM technique would still need evidence showing which patients benefit, how often it works, and whether it improves live birth rates without adding unacceptable risks.
The same evidence-first approach applies to every emerging fertility technology. Our guide to evaluating IVF add-ons and their evidence offers practical questions patients can use when a treatment is described as innovative or promising.
Hope With a Clear View of the Evidence
Research like this matters because it expands what scientists can investigate. It may eventually inform new fertility-preservation options for people affected by cancer treatment, diminished ovarian function, or other circumstances that limit access to mature eggs. It also helps researchers understand how follicles and eggs develop outside the body.
At Her Serenity, we believe meaningful advances in fertility care deserve both hope and careful explanation. Patients should hear what new research may make possible, what remains unknown, and how far a discovery is from everyday clinical care.
For now, this technique belongs in the research setting. Its greatest value today is not as a treatment promise, but as evidence that scientists may be able to use a much earlier stage of egg development than conventional IVF currently allows. Continued research will determine whether that possibility can become a safe, effective, and responsible option for people in the future.