A family in England is celebrating the arrival of twins - who were born two years apart.
Oliver Best, two, and his new-born brother Isaac were conceived at the same time through IVF and are considered to be twins as they were born from the same batch of embryos.
Their parents, Rachael and Richard Best, had been trying for a child for four years and had already gone through six attempts at IVF before she became pregnant.
On the seventh cycle, full-time mother Rachael gave birth to 7lb 6oz Oliver in March 2014 with another two embryos then frozen at Leicester Fertility Centre.
The 35-year-old said: "We tried naturally for four years to no avail, then we went through a year of different tests and it came back as unexplained infertility which was devastating because we didn't know what was wrong.
"We started the gruelling process of IVF. We had six rounds which resulted in a culmination of either it worked and I miscarried early on or it failed."
The couple then had a "last-ditch attempt" which resulted in Oliver, with a further cycle leading to the birth of brother Isaac nearly two years on, weighing 8lb 9oz.
Most twins share a birthday and Oliver and his brother were close as Isaac was due on March 22.
But he ended up arriving five days early and is settling well in the family home in Leicester.
Mrs Best said: "They were born two years apart almost to the day, it's really extra special.
"He's sleeping fantastically and Oliver is brilliant with him.
"It's really surreal because they are two years apart, but when I look back at photos of Oliver at Isaac's age you really notice the resemblance in them, it's quite amazing.
"We were worried about how he would react because Oliver has had our sole attention for the past two years but he's fantastic, always hugging him. Every time Isaac cries he is there like a shot."
Mrs Best and her husband, who works as a transport engineer, had one round of IVF treatment on the NHS and then had to pay privately for subsequent rounds.
She said: "It's really difficult. Prior to the first time, I think I had blinkers on because I thought, 'it's going to work, they're putting an embryo back inside me, it's essentially a baby, why wouldn't it work?'"
"The first time it did work and that was one of the miscarriages, and after that is when I realised it wasn't necessarily going to happen and it's really devastating, but we had great support of family and friends."
She added her message to other couples experiencing problems having children was to "not give up hope".
She said: "It's fantastic and definitely worthwhile. It's complete mayhem pretty much all of the time but it's completely worth it."
Consultant embryologist for Leicester Fertility Centre Jane Blower said: "We are delighted to hear Rachael and Richard's good news and would like to congratulate them on the safe arrival of Isaac."