Elton told Hello!: "Both of us have longed to have children, but the reality that we now have two sons is almost unbelievable.
"The birth of our second son completes our family in a most precious and perfect way.
"It is difficult to fully express how we are feeling at this time — we are just overwhelmed with happiness and excitement."
The Sun revealed in November that Elton and David were expecting their second child by the same woman who carried Zachary.