The 33-year-old singer, who already has a son from previous relationship, flaunted her growing baby bump in a little black dress while performing at the New Orleans Jazz & Heritage Festival on May 2, reported Ace Showbiz.
During the more-than-an-hour set, Aguilera performed 'Lady Marmalade', 'Ain't No Other Man', 'Candyman', 'Beautiful' and 'What a Girl Wants' among others.
She had brought A Great Big World's Ian Axel for their collaboration, 'Say Something'.
The singer also covered songs including Maroon 5's 'Moves Like Jagger' and Led Zeppelin's 'Whole Lotta Love' among others.