I don't understand why adoption isn't more prevalent

I don’t understand how in today’s overpopulated society so many people still choose to have children. Every time that choice is made, another child will grow up in an orphanage. We should be letting these children into our lives and giving them the love that they deserve. Of course it’s special to have your own child, but imagine the suffering a  parentless child goes through. Particularly in the third world, being an orphan can mean going through a very hard life. If less than one in ten couples adopted, there would be no more orphans. Save the planet, adopt a child.