A small number of fertility clinics around the world are offering a controversial treatment: a procedure to provide clients’ embryos with donated mitochondria as a way to increase their chances of taking home a baby.

The method, called mitochondrial replacement therapy (MRT), involves removing the nucleus from a person’s egg or a couple’s single-cell embryo and transplanting it into an egg from a young donor. The theory, which has not yet been tested in rigorous clinical trials, is that the donor’s mitochondria could help the egg, after being fertilized, or the embryo mature. Any resulting babies would have nuclear DNA from their biological mothers and fathers and mitochondrial DNA from the egg donor.

Scientists have already shown in a clinical trial that MRT can produce healthy children for parents whose mitochondria carry disease-causing mutations. But Nature has identified clinics in Asia, Europe and America that advertise MRT to increase the success rate of in vitro in vitro fertilization (IVF) for a broader range of clients who do not have such mutations. “MRT can transform your fertility journey,” says the website of an agency called International Fertility Group at the time of this article’s publication. The agency helps people find and receive services from fertility clinics around the world. (An agency spokesperson said MRT is not performed by the agency itself but by partner clinics.)

It is difficult to confirm that all of these clinics are actually performing the procedure. But they are announcing it on their websites and social media channels. Doctors and scientists (including some who think MRT shows promise) generally agree that this therapy is experimental and should currently be offered only as part of a clinical trial.

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“I’m pretty horrified,” says Richard Anderson, a fertility doctor at the University of Edinburgh, UK, after reviewing the MRT offering from one of the clinics identified by Nature. He says the technique is difficult, the risks are high and the benefits uncertain.

“They are offering the treatment (usually a very expensive treatment) to people who are desperate to have their own baby,” despite the absence of published evidence from controlled trials supporting its use for infertility, says Mary Herbert, a reproductive biologist at Monash University in Melbourne, Australia, who led a clinical trial involving MRT. “It’s fundamentally wrong.”

Uliana Dorofeyeva, clinical director advisor at the International Fertility Group, defends the practice. “This is the patient[’s] right to choose the method and to choose the way they would like to resolve their fertility problems,” he says.

With MRT added to standard IVF, “a 40-year-old now gets similar results to a 25-year-old,” says Kent McQueen, CEO of IVF Asia Group in Makati City, Philippines. “It’s like miraculous results.”

Improving the odds

The first baby conceived with MRT was born in 2016, to a woman who had lost two children to mitochondrial disease.¹. Last year, in the first clinical trial of MRT to prevent the inheritance of mitochondrial diseases, an independent research group reported the birth of eight healthy babies.².

Mitochondria provide energy to cells, leading to theories that mitochondria from young donors could also increase the success rate of IVF. That rate drops rapidly with age. According to 2024 statistics from the American Society for Assisted Reproductive Technology, transferring a first embryo into the uterus of a woman between the ages of 35 and 37 resulted in a live birth 26% of the time. But for women ages 41 to 42, the rate was 8%.

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Some fertility clinic websites claim that replacing mitochondria in older eggs will improve those odds. The clinics point to a study that suggests MRT could help the eggs of subfertile mice develop into healthy puppies.³. “While [a] “As cells age, we lose the capacity and performance of mitochondria,” says Dorofeyeva, adding that “there is a mitochondrial disorder associated with aging.” “We can safely say that this is a secondary mitochondrial disorder.”

But Nature found only a few published studies investigating the use of MRT as a treatment for infertility in humans.

A study from 2023⁴ examined MRT in 25 people without mitochondrial disease and reported that 3 of the 6 participants under the age of 36 gave birth to a baby. Of the other 19 participants, who were between 36 and 39 years old, only 3 did so. The study’s lead author, Nuno Costa-Borges, CEO of Embryotools in Barcelona, ​​Spain, says it is not possible to draw conclusions about the effectiveness of MRT from the study due to the small sample size. The study also lacked a control group.

A 2019 study reported a single birth among 30 participants. It also lacked a control arm and did not recommend the procedure.⁵.

Hopes and doubts

It is unclear how many clinics around the world offer the procedure.

Nature identified clinics in the Bahamas, Philippines, Albania and Ukraine that advertise MRT online, sometimes simply calling it “oocyte rejuvenation.” A clinic called BioTexCom, based in kyiv, offers packages starting at €6,500 ($7,400) for a single transfer of an embryo created using MRT to a parent’s uterus.

BioTexCom did not respond to NatureThe request for comment on scientists’ view that charging patients for MRT is premature given the experimental state of the evidence.

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Some researchers think MRT is promising. The intervention could improve an egg’s ability to develop, Costa-Borges says, “leading to a greater proportion of embryos reaching the blastocyst stage,” the early phase of development in which embryos implant in the uterine wall.

But other scientists interviewed by Nature They are deeply skeptical that MRT can be useful. Robin Lovell-Badge, a developmental biologist at the Francis Crick Institute in London, says there is “no justification” for using MRT to treat infertility. “There is little to no evidence” that eggs from women seeking infertility treatment have too few or low-quality mitochondria, he says. Lovell-Badge says it is “possible” that older women have “secondary mitochondrial disorders” that affect cells in the ovary, which could lead to infertility. But he is skeptical that MRT can treat the condition.

Clinic data

Clinical doctors affirm that their figures show good results. IVF Asia Group sent Nature an unpublished summary without data tables saying that after MRT, 50% of fertilized eggs became blastocysts. McQueen said “pregnancy rates are pretty good” and said he couldn’t share more details.

Another source of information is a summary of the 2025 conference.⁶ by Dorofeyeva and co-authors whose listed affiliations include the International Fertility Group and other clinics. The abstract reports pregnancy rates of 55% or higher for IVF plus MRT, but the study was based on a “selected group of patients” chosen “based on their uterine capacity, their previous results, and how many cycles they had,” Dorofeyeva says. “It must be clarified that these are not general statistics,” he says. He declined to provide a more representative success rate, saying it is “very complicated.”