A controversial IVF technique could see babies being born with three parents, scientists have suggested.
The technique is banned in Britain
Experts in China say they have created embryos using eggs from two women and sperm from one man.
The embryos were implanted into a 30-year-old Chinese woman with fertility problems.
While she suffered a miscarriage, scientists believe the technique could help other women.
It is the first time scientists have used the technique since it was outlawed in the United States in 1998. The procedure is also banned in the UK.
The woman had previously undergone two IVF cycles. However, these failed because of problems with her eggs.
Scientists at Sun Yat-Sen University, in Guangzhou, tried to overcome this problem by fusing the woman's egg with one from another woman.
Eggs consist of a nucleus which holds most of their DNA and surrounding material called the cytoplasm.
Scientists removed the DNA material from the donor egg leaving just the cytoplasm. They then put the nucleus of the patient's egg into the donor egg, in a process called human nuclear transfer.
These fused eggs were then fertilised with the man's sperm. In all, the scientists transferred five of the three-parent embryos into the woman.
She subsequently became pregnant with triplets. One month into the pregnancy, doctors aborted one foetus to give the remaining two a better chance of survival.
However, the remaining two were both delivered prematurely and died at four and five months into the pregnancy respectively.
The scientists said the deaths were not related to the IVF technique they used, but rather due to complications as a result of a multiple pregnancy.
They believe the technique could be invaluable to women whose eggs are not healthy enough to support a normal pregnancy.
However, critics have attacked the experiment and accused the scientists of taking a major step towards human cloning.
"The potential for abuse of this type of technique could be mind-blowing," a spokesman for pro-life group Life said.
The technology behind the Chinese experiment was developed in the United States.
However, scientists there stopped their work after the Food and Drug Administration cracked down on fertility experiments.
China has now announced that it too will outlaw embryo research.
The Human Fertilisation and Embryology Authority, which regulates IVF in the UK, said the law outlawed such experiments.
"This type of experiment couldn't be carried out in the UK," a spokeswoman told BBC News Online.
"Under the Human Fertilisation and Embryology Act, you can't mix genetic material from three different people."
Dr Mohammed Taranissi of the Assisted Reproduction & Gynaecology Centre in London said the technology had been around for a while.
"If you look at it from a purely medical point of view it could benefit people who have problems conceiving," he said.
"But from the ethical point of view, I am not sure I would be comfortable using it. It is not something I would like to try."
Details of the experiment were presented at the American Society for Reproductive Medicine annual conference in San Antonio, Texas.