Meghan Trainor's sons are thrilled to have a sister

She told People: "They are over the moon. Riley takes his 'big brother' role very seriously, and Barry is just so gentle and curious with her. Watching them bond with their sister has been one of the sweetest parts of this whole experience."

And Riley - who, with Barry, chose their new sibling's name - cannot wait to tell his school class about the new addition to his family.

Meghan - who met Daryl at a house party in 2014 - added: "We printed out photos for Riley to bring to school and show his entire class, and he couldn't have been more excited."

The Grammy award winner - who started dating the Spy Kids star in 2016 after they were set up by actress Chloe Grace Moretz - is delighted she has a girl.

The Mother performer - who got engaged to Daryl on December 21, 2017, the day before her 24th birthday, after he popped the question under a Christmas lights tunnel - said: "It feels surreal.

"I've dreamed about this for so long, and now I'll look at her and still can't believe she's real. My heart feels fuller than I ever knew it could."

Meghan and Daryl - who got married in front of 100 close friends and family in a backyard ceremony at their Los Angeles, California, home on her 25th birthday - used a surrogate to welcome little Mikey into the world because it was the "safest" option.

Meghan explained: "It wasn't our first choice, but we had endless conversations with our doctors on this journey, and this was the safest way for us to be able to continue growing our family. We are forever grateful for that option.

"I want people to know that surrogacy is just another beautiful way to build a family. It's not something to whisper about or judge. It's rooted in trust, science, love, and teamwork. Every family's journey looks different, and all of them are extremely valid."

On Tuesday, the mom-of-three announced the arrival of Mikey on Instagram.

She captioned a series of photos of the family bonding with the newborn with: "Our baby girl Mikey Moon Trainor has finally made it to the world thanks to our incredible, superwoman surrogate.

"We are forever grateful to all the doctors, nurses, teams who made this dream possible. We had endless conversations with our doctors in this journey and this was the safest way for us to be able to continue growing our family. (sic)"

Mikey's older brothers chose her unusual middle name.

Meghan added: "We are over the moon in love with this precious girl. Riley and Barry have been so excited, they even got to choose her middle name. We are going to enjoy our family time now, love you all. (sic)"

The Made You Look singer has made no secret of her desire to have more children, and she admitted a year ago she was ready for "some daughters".

She told People magazine: "Where I am right now is far beyond anything I could have ever dreamed of.

"I always wanted a family. Check. Now I need some daughters.

"But I never thought I could be a pop star because I didn't believe in myself.

"Now, 19-year-old Meghan putting out 'All About that Bass' is stoked; she's so proud, like, 'I didn't know you could do that.' It took 10 years to become brave, but I'm finally thriving."