As part of a series of articles BBC News Online health reporter Jane Elliott looks behind the scenes of the NHS.
Tom (right) is now thriving
This week we focus on a couple who had to make an agonising decision about whether to continue with a pregnancy when they discovered their unborn child had a congenital heart defect.
Debora Henigan was five months into her second pregnancy when doctors delivered the devastating blow that her unborn baby had a problem with his heart.
A routine scan had shown that one of the chambers of the heart was enlarged and the sonographer thought Debora and husband Mike should be booked in to see the specialist.
The couple faced a worrying weekend, knowing that baby Tom had some sort of heart problem but unaware of how serious it could be.
On the Monday morning they saw specialist Dr Piers Daubeney, consultant paediatric and foetal cardiologist at the Royal Brompton and Chelsea and Westminster, London.
He told them that Tom had pulmonary atresia intact ventricular septum - a blockage of the pulmonary artery carrying blood to the lungs.
He warned them the condition could deteriorate during pregnancy and listed their options, which included considering a termination.
The couple were also advised to have an amniocentesis to see whether their baby also had a chromosomal defect, such as Down's Syndrome.
Debora said the wait for the test results was terrifying. The diagnosis had catapulted them from a normal pregnancy into one that was high risk.
"My first pregnancy, with Angus, was completely trouble-free and I just assumed everything would be fine again.
"The 20 week scan just came as a complete shock. "
She said Dr Daubeney had treated them compassionately, but had laid all the cards on the table, ensuring they properly considered all the possibilities.
"We were not given any false hopes but when you are in a situation like that you do want something to cling onto.
"But on reflection I would always want to be told all the options, even though we did have a lot of heartache in considering them.
'State of shock'
"Dr Daubeney was incredibly supportive, but he had to be clear about what the options were. And we were shocked to hear that termination was an option.
"He also had to say that there was a chance that we could lose the baby.
"We were trying to take all the information in, but we were in a state of shock."
The couple were worried they could lose their baby son
Mike said that one of the big difficulties was that because Tom's condition had been diagnosed so early, it was impossible to tell how it would progress.
"Originally it was very difficult to pick up and they had no idea how it would develop," he said.
"The fact that it was picked up was down to the expertise of the sonographer."
The test for Down's came back clear.
Debora said: "I think so much hinged on the amnio and the results of the amnio took away the decision from us.
"If the results had been bad we knew we would have had to face up to the abortion decision. It was terrifying.
"Prior to my pregnancies I did not have any strong views on termination, but then I had seen the baby on the scan and it would have been a very hard decision to make."
The couple spent the rest of the pregnancy watching and waiting to see how their little boy's heart would develop, but in the knowledge that in-utero surgery might be needed.
Mike said: "With each scan we had a slightly better idea of what was going on, but the doctors said it was only when Tom was out that they would be able to know the range of disability that he might have. And as time went on it became more encouraging."
The operation was a great success
But he admitted that the fear that he might lose his son at any minute prevented him bonding as closely with the foetus as he had with his first son three years before.
"I don't think I kissed the tummy much or bonded with Tom until he popped out. I think I was subconsciously keeping my distance."
Debora agreed: "I did not feel I was bonding with the baby because there was always the possibility that I might lose it.
"But then on the other hand we had to be positive about the baby and to protect it."
The couple decided to have an induced birth so they could ensure that all the specialists were on hand to help them.
Just three days after he was born Tom needed open heart surgery.
But the operation was a great success and the future looks bright for the little boy, who is now 15 months old, although he will probably need at least one further operation when he is older.
"We were just very lucky the way it turned out," said Mike.
Tom is a very lively toddler
Debora added: "I thought I was going to bring home this sickly child, but it was completely the opposite. He is a little demon, who never stops. And the doctors say he should have a perfectly normal life."
Dr Daubeney says he makes women aware of all the options they face and monitors them throughout their pregnancies.
He tells them about the condition and has to make a decision on whether to operate on the baby in the womb.
He said that in Tom's case it was possible to wait until he had been born to carry out the surgery, but that if his condition had deteriorated in the womb he may have had to act sooner.