Approximately one in every hundred babies born has some form of congenital heart defect (CHD).  Of these, less than 5% are HLHS.  The severity of HLHS can vary tremendously, from a slightly undersized ventricle to a virtually non-existent ventricle.  It is estimated that approximately 1 in every 5,000 babies is born with HLHS requiring medical attention.  

That translates to approximately 2,500 cases of HLHS each year in the United States, with 20 times that number worldwide.  In many parts of the world, most HLHS babies are never diagnosed.  And those who are diagnosed have a very slim chance of receiving medical attention.  This is why it is so important to support and donate to Gloria's Place of Hope or other agencies who provide medical care for foreign babies.  

There are many theories on what causes HLHS.  As yet, no link has been found to behavioral or regional sources.