One in 100 babies will have congenital heart disease.
Congenital heart disease is the most common birth defect among babies.
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For every 100 babies born in the world, one of them with have congenital heart disease.
According to Dr. Joel Kirsh, paedeatric cardiologist at the Hospital for Sick Children, it's the most common birth defect.
"It's a wide variety of disorders and a lot of them are fairly rare but when you add them all up they make up the most common defect in live born infants," Kirsh said.
Congenital heart disease is the umbrella term that describes any kind of heart disease or defect that a child is born with. Kirsh said these can include holes in their heart, valves that haven't developed properly and more complicated ones that comprise combinations of different areas of the heart not developing normally.
They can extend from straight-forward conditions such as blue baby condition, where the large arteries connected to the heart are reversed, up to conditions such as hypoplastic left heart syndrome, where one side of the heart, so two out of the four chambers, fail to develop.
Congenital heart disease begins in utero and happens while the heart is developing into its final form. Kirsh said the heart has to make some complicated transitions to become a combination of four chambers, four valves, two large arteries and a number of veins connecting to the heart.
"So the embryology, which is the scientific term for the development of the heart during pregnancy, is quite complicated and even a small change early on, even when the heart is still microscopic and the baby is still almost invisible, even a small change in how the heart folds and turns on itself to develop can result in a very dramatic abnormality at birth," he said.
While congenital heart disease in babies is common, Kirsh said only a minority of cases can be linked to genetics, however, they are beginning to understand more of the predisposing factors but still have a long way away in being able to tell in whose family there's likely to be a problem.
What they do know is there are certain conditions that increase the chances of having a child with heart disease and one of the most common and well-known one are babies with Down syndrome. They are at a higher risk than babies without Down syndrome to have congenital heart disease.
The good news is doctors can detect heart disease early on by doing a fetal echocardiogram, which is an ultrasound of the heart of the baby while it's still in the mother's womb, and Kirsh said there are a number of reasons why a woman may want to have one.
"If she has a standard ultrasound of the baby, to look at the baby's growth and development...there may be a concern or suspicion that prompts referral for a more detailed look by a cardiologist or there may be a family history of heart problem," he said.
In these cases, it's a good idea to have the test so doctors can anticipate if the child will have a heart condition. Kirsh said while some of the conditions are not particularly dangerous early in life, some of them can be if not detected early.
Kirsh said early detection means doctors can have a plan and be prepared when the baby is born.
"If we know about the heart condition, we arrange for them to be born close by to Sick Kids, usually at Mount Sinai, and we bring the babies over here immediately," he said.
And treatment doesn't have to wait until the baby is born.
"Because the baby is connected to the mother's circulatory system and its doing all the provisions of oxygen and blood pressure, but there is work being done in trying to correct abnormalities earlier in utero life in the hopes that they'll be less severe when the baby is born," he said.
However, Kirsh said in the majority of cases nothing needs to be done until the baby is born
Kirsh said in the past 25 years, there have been great advancements in treatments, for example, using a catheter, which is inserted in the vein in the baby's leg and threaded into the heart under X-ray. This carries several advantages such as less invasiveness, quicker recovery times and fewer complications.
"We're capable of doing a number of things with a catheter, which doesn't involve a big incision in the chest and doesn't involve having to put the heart on the heart-lung bypass machine (a machine that takes over the working of heart), we can relieve a lot of the same sort of conditions that used to be the realm of the surgeon in the past," he said.
Kirsh said the other advancements are more treatment options and better chances for children with the most severe or complicated heart diseases.
Kirsh said 20 years ago, those children's conditions would have been fatal.
As well, doctors now have a better understanding about the issues that could arise after you treat congenital heart disease.
"The potential side affects of heart-lung bypass machines in periods of time with low oxygen levels and what those can mean for future challenges like learning disabilities," he said.
Adding doctors now know how treatments can affect babies' brains, hearts and other vital organs so there is less risk of long-term problems such as motor, speech and language delays.
Kirsh said there are few conditions they don't have treatment for today, but prognosis depends on what condition babies have. Some such as hypoplastic left heart syndrome used to be almost always fatal, while other diseases that had anywhere from a 25 to 50 per cent survival rate are now up to 90 per cent survival rate.
Kirsh said learning your baby has congenital heart disease is a jarring and shocking experience, particularly if they aren't aware of it until after the baby is born. He said the first year of their babies' lives can be the most challenging, but rest assured most of them will grow into strong, healthy children with few limitations.
"By the time the kids are school age, while the parents have not forgotten that they have a child with a heart condition...they are much more comfortable because they've educated themselves and they've realized their child is going to have a good outcome."