Nurses take care of a newborn baby at the Tangdu Hospital in Xi'an, capital of northwest China's Shaanxi Province, Feb. 24, 2016. The baby, born on Wednesday in Xi'an through frozen embryo transfer (FET), was fertilized over 12 years ago and became China's longgest preserved tube baby through FET technology. (Xinhua/Liu Tingting)

WASHINGTON, Oct. 26 (Xinhua) -- The world's first children who were born in the United States under a now-banned practice of creating three-parent embryos are "in good physical and cognitive health" more than a decade later, a study said Wednesday.

The findings, published by the journal Reproductive BioMedicine Online, were based on the first survey that described parents' perception of the well-being of their children after the use of the experimental fertility procedure called cytoplasmic transfer.

"The survey-based study is the first to explore the long-term impact of cytoplasmic transfer and the results appear to be positive," said Serena Chen, Director of the Institute for Reproductive Medicine and Science at Saint Barnabas Medical Center in New Jersey, which conducted the study with the ART Institute of Washington.

"So far, only one child was informed by parents about the innovative science behind their conception. As more parents decide whether to tell their children, we may be able to conduct additional studies in the future," Chen said.

Cytoplasm is the liquid portion of an egg that contains many different molecules and tiny parts called organelles, including mitochondria that generate energy for the cell.

During cytoplasmic transfer, a small amount of cytoplasm from a fertile donor egg is injected into the egg of a woman who is trying to become pregnant through in vitro fertilization, or IVF. The egg is then fertilized with sperm and implanted in the uterus.

Between 1996 and 2001, Saint Barnabas Medical Center offered women who had experienced multiple IVF failures and poor in vitro embryo development the opportunity to try this experimental technique.

Thirty-three couples participated in the study and 13 of the 14 women who became pregnant delivered 17 babies, all of which reported to be healthy at the time of birth. But the technique was later halted by the U.S. Food and Drug Administration.

In the new study, parents of 13 children whose ages ranged from 13 to 18 years were asked about the physical, emotional, mental and cognitive well-being of the children through an online questionnaire.

The survey found parents had no concerns about the cognitive development of their children and felt their children were in good health.

"The majority of children (11/13) had excellent grades. The other two had good grades," it wrote.

Meanwhile, no major health issues were found.

Minor health issues among the children included allergies (seven children), minor vision (three children) and skin (three children) problems, mild asthma (two children), and chronic migraine headaches (one child).

One boy was diagnosed with borderline attention deficit disorder. He also has episodes of depression. But the researchers said his family has a history of depression.

They noted that limitations of the study included the subjective nature of the survey and the lack of clinical follow-up.

Recently, John Zhang of New Hope Fertility Center in New York revealed the birth of the first baby, now six months old, using a different three-parent technique called mitochondrial spindle transfer.

The new approach involved removing the nucleus from one of the mother's eggs and inserted it into a donor egg that had had its own nucleus removed. The resulting egg was then fertilized with the father's sperm.

Unlike cytoplasmic transfer, this procedure was aimed not at infertility but at preventing women with devastating mitochondrial disease from passing them on to their children.