A representative of the 42-year-old singer confirmed the news of Lopilato pregnancy following tabloid reports in her native country Argentina that speculated about it, reported EOnline.
The couple married in 2011 and already have two sons, four-year-old, Noah and two-year-old Elias.
In November 2016, Buble had revealed that his son Noah was diagnosed with liver cancer and was receiving treatment in US.
Noah diagnosis had led to Buble cancelling various press appearances, including hosting the BRIT Awards last year.
In April last year, Buble had said that Noah was on the path to recovery.