Singer John Legend and his wife Chrissy Teigen have announced they are expecting their second child.

In a touching Instagram post, the couple’s one-year-old daughter Luna helped them make the big revelation.

With the camera pointing at her tummy, Teigen asks: “Luna, what’s in here?”

“Baby,” the toddler replies, stroking her mother’s stomach.

it's john's!

A post shared by chrissy teigen (@chrissyteigen) on Nov 21, 2017 at 1:15pm PST

Teigen cheekily captioned the photo “it’s john’s!”, and was flooded with congratulatory messages from her followers.

One fan wrote: “I’ve suspected! You’re with that pregnancy glow. Congratulations and may your baby be very happy.”

Another said: “Yay! I’m so happy for you!! Luna is going to be the best big sister!”

Legend, 38, also posted a link to the Instagram photo on Twitter, alongside two baby emojis and two love hearts.

Luna was born in April 2016 after model Teigen, 31, opened up about their fertility struggle and how she had undergone IVF treatment.

The couple married in 2013.