A couple who tried for a baby for a decade have become the first in the country to give birth after using a pioneering new method for screening IVF embryos.
Louise and Andrew Riley's "miracle" baby son Elliott was born just after Christmas, making him the first child outside America to be successfully delivered as a result of a new type of genetic testing.
Mrs Riley, 37, said they opted for the £8,500 procedure because it was their "last hope" after "undergoing numerous test and a failed cycle of IVF".
The method involves taking sample cells from a five or six-day-old IVF embryo, called a blastocyst, to see if they contain the right number of chromosomes, and then cross-matching the genetic information with the DNA from both parents to look for related faults.
Every cell in an embryo should have 23 pairs of chromosomes - bundles of DNA - one set from each parent.
However, very often an embryo has an extra chromosome or is one short, a fault called aneuploidy.
Embryos with chromosomal abnormalities are usually spontaneously aborted. Aneuploidy is thought to cause six out of seven miscarriages and the chance of problems increases significantly with a woman's age. Aneuploidy is the principle reason why success rates for standard IVF - where unchecked embryos are implanted - remain at about 30pc.
Babies with the wrong number of chromosomes that survive have genetic problems including Down's, Edwards' and Patau syndrome.
Chromosome screening is a relatively new procedure. It started by checking the six or seven chromosome pairs that most commonly produce faults.
This new technique, undertaken by doctors at Care Fertility, a private Manchester clinic, checks all 23 pairs and results in a higher success rate.
Genetic information from the embryo sample cells is also cross-matched against DNA samples taken from the parents to check for additional faults, a process called "parental support".
Early results suggest the combined method improves the chance of a viable ongoing IVF pregnancy from about 30 to 75 per cent.
Mrs Riley, 37, and her husband, 39, from Lancashire, said it meant they were "finally blessed" with a baby on December 30.
She said: "The last 10 years have been a very emotional and difficult period of our lives.
"We have been unable to conceive despite undergoing numerous tests and a failed cycle of IVF.
"Many friends and family have had children during this period and whilst being extremely happy for them, it was heartbreaking for us.
"We approached Care as a last hope. On 30th December we were finally blessed with a baby son Elliott.
"We find it hard to express just how happy we are as he is our little miracle."
Dr Mark Sedler, who is leading a trial of the new technique, said: "The technology we used to analyse the embryo here has never been used outside America. This is testing the whole building blocks of what could be a life."
While a handful of babies have been born in Britain after all chromosome sets have been checked - known as full array comparative genomic hybridisation (CGH) - he said Elliott was the first baby born using "parental support" as well.
Dr Sedler said "parental support" identified a number of chromosomal abnormalities not identified by full array CGH on blastocysts alone.
For instance it checked for haploidy and polyploidy, where an embryo has 23 and 69 chromosomes respectively. It also identified a rare condition called uni-parental disomy, where an sperm enters an empty egg and divides, or two sperm enter an egg, which can both result in a phenomenon called a complete molar pregnancy.
Embryos with such faults will never result in a successful pregnancy, he said.
"Parental support" also helped doctors pick the embryo with the best chance of success, by increasing the confidence that it did actually have 46 chromosomes, he said.
In addition, it could be used to see whether an abnormality came from the mother, father or both.
He said the "parental support" element of the test only cost an additional £300.