As a Ukrainian clinic claims success in creating babies with three parents’ DNA, critics are raising medical and ethical objections to the largely experimental fertility method.

“This is really an irresponsible kind of human experimentation,” Marcy Darnovsky, the head of the Center for Genetics and Society.

“We just don’t know what’s going to happen to these children,” she said, according to NPR.

Dr. Valery Zukin, director of the Nadiya Clinic in Kiev, Ukraine, is among the team of doctors who have created four children using DNA from three different parents — a procedure that has not publicly been done anywhere else in the world. Three more of Zukin’s patients are pregnant by this method.

The technique entails fertilizing a woman’s egg with her partner’s sperm. The resulting embryo is placed on a dish with a second embryo, which was made using sperm from the same man and the egg of a different woman, an egg donor.

Throughout the process, most of the DNA from the donated egg is removed and replaced with the would-be parents’ DNA. This embryo is then implanted into the womb of the patient wishing to conceive.

The procedure was originally created for women who had devastating genetic disorders caused by mitochondrial DNA defects to help avoid passing these genes on to their children. However, the technique has evolved over time from its original purpose and is now being used by parents without a mitochondrial disorder.  

Locals in the Ukraine are charged around $8,000 for the procedure, while out-of-country patients pay upwards of $15,000. The first-known child conceived by this method is now 15 months old. The baby’s mother, known only as Tamara for privacy purposes, said she was “so excited” to have a child after a long road of fertility issues, according to NPR.

Dr. Zukin, a pioneer in the method, does not see an ethical problem with the fertility procedure, saying that he is only helping families achieve genetic connection with their children.

“If you can help these families achieve their own babies, why must it be forbidden?” Zukin asked.

“As a doctor I understand only one thing: we have parents who couldn’t have children and now they have their own biological child. That’s all,” he continued.

While Zukin and his clinic of scientists are believed to be the first to create living children with DNA from three parents, experiments surrounding the technique have been a topic of controversy for years.

In 2015, the Catholic Bishops of England and Wales said there were “serious ethical objections” to the embryo techniques, noting “the human embryo is a new human life, and it should be respected and protected from the moment of conception.”

Other controversy has been associated with the procedure, including a 2016 case when a woman traveled to Mexico where “there were no rules,” to receive the fertility treatment that would evade “existing regulations in the United States.”

In 2014, the Center for Genetics and Society penned a letter to the FDA saying the technique “should not be permitted because of the profound safety, efficacy, policy and social problems [it] would pose,” by “bringing children into existence by experimental techniques that have had developmentally poor outcomes in studies using both animal and human eggs.”

Darnovsky voiced concerns that allowing scientists to make inheritable genetic modifications opens the door to “designer babies.”

“What we’re seeing is a fast slide down a very slippery slope toward designer babies,” she said.

Jeffrey Kahn, director of the Johns Hopkins Berman Institute of Bioethics, also voiced his concerns over the method, saying “we just don’t know if it’s safe,” according to NPR.

“This is the first time a human being is being created this way,” he said, adding “this is an uncontrolled experiment in which women are being offered a new technology that’s never been tried before. That’s why it’s a concern.”