Two sets of identical twins - two boys and two girls - have been born to a US woman, herself a fraternal twin.
The two twins were born against mind-boggling odds
The doctor who delivered Geana Morris' babies put the odds of such an event at one in a million quadruplet births.
The mother and babies were all doing well, officials at the Lankenau Hospital in Pennsylvania said.
Ms Morris was implanted with two embryos in January in the hope that one of them would become a baby, the Associated Press agency reports.
Heightening the coincidence, the four babies were born to Ms Morris on her 34th birthday.
"It's a very special 'birth' day for me," Ms Morris said.
The babies, each weighing between 2 and 3lb (0.91-1.36kg), are receiving medical help with their breathing and could be sent home from hospital by late September, doctors said.