Singaporean singer-songwriter Tay Kewei is four months pregnant with baby number two.
The 36-year-old is married to local singer Alfred Sim, 38.
The couple revealed the news yesterday - the same day they released their new Mandarin single, MoMo I Love You.
In a press release, Cross Ratio Entertainment, which manages the couple, said they are "delighted yet excited to embrace a new phase of their lives".
The new duet is inspired by their two-year-old son MoMo, who often appears in the couple's social media posts, and expresses their love for the boy with lyrics such as: "Want to grow up with you" and "When my hugs are no longer needed/ remember that you are my pride".
Its official music video features clips of the couple playing with MoMo and travelling together and ends with a shot of the whole family at home.
In that shot, MoMo holds a drawing of a family of four, hinting at the upcoming new arrival.
He also says: "There is a baby in Mama's tummy", to smiles from his parents.
The couple recently performed at the Starker Music Carnival in November last year, when they took MoMo on stage and performed the duet Thought That.
While MoMo, whom Sim carried in his arm, did not sing, he waved to the audience.
Sim and Tay will take the stage again at a free TGIF Music Station performance at 8.45pm on Feb 7 at Singapore Sports Hub's OCBC Square.