A Lincolnshire woman has had triplets, two years after the birth of her first daughter from the same set of eggs, making them quadruplets, doctors said.
Experts at Nottingham's Care Fertility Clinic described the latest births as "most unusual".
The Baxter family, from Grantham, said they were "gobsmacked" by the arrivals.
"It is most unusual to see a set of triplets born from frozen embryos after a successful previous pregnancy from the same batch," a Care spokesman said.
The babies' mother, Helen Baxter, had frozen her remaining embryos after falling pregnant with Alice, now two, and then doctors defrosted them and put three back.
Alice now has sisters Niamh and Maisie and a brother, Noah, who were born in January.
We run a big unit and we have never seen anything like it before in... 15 years Ken Dowell, Care Fertility Clinic
"We were gobsmacked," Mrs Baxter said. "It was a complete shock. We never imagined that we would end up with three babies from that same batch.
"We went through the first cycle of fertility treatment and they harvested nine eggs from me, of which eight were fertilized.
"We put two back in and we got Alice.
"When we went through the cycle again they put three back in."
Mrs Baxter said: "We have had to buy a new car obviously to accommodate everybody. We have had to go out and buy three of everything - which has been a bit of a shock."Source