Four identical baby girls were born last week in Shanghai, at the Shanghai Red House Ob & Gyn Hospital at about 5 p.m.
The girls were delivered by Caesarean section after 31 weeks. They are all healthy and weigh about a kilo each.
The obstetrician, Shen Jie, said that the babies' condition is better than expected. She added, "Although their weight is not enough, their maturity is good. Only one child breathes with ventilator when being transported."
The babies had to be transported to a children's hospital. Two of them were in ventilators, while all of them had to remain in the intensive care unit.
The babies were conceived via in vitro fertilization.
A couple from Canada also had identical quadruplets in May. The quadruplets were all girls and delivered via Caesarean section as well.
The father admitted that the babies are so identical it's so hard to tell them apart. He said, "Even just holding two side by side, I can't tell them apart at all. It's really hard."
The Canadian couple are first-time parents.
Multiple births, identical triplets and quadruplets are becoming more frequent because of in vitro fertilization. Without it, the chances of having identical triplets or quadruplets is 20 to 30 in a million births.
According to the United States Health Services, twin births have increased by 75 percent since 1980. This has been a more common phenomenon with couples who underwent fertility treatments.
The case is also true in China as more Chinese couples are taking fertility treatments. This is according to the obstetrician in Shanghai, where an increase in the number of identical quadruplets took place between 2004 and 2008.
In the case of both mothers in Canada and Shanghai, the fertilized egg split four times. This is why the quadruplets are all identical.