Pattie Mallette has "thanked the lord" for her first grandchild

She wrote on Instagram: "Oh my heart! Welcome, baby Jack. I love you so much! Thank the lord. What a miracle!" and emblazoned her post with a string of emojis.

Pattie then took to X - which was previously known as Twitter - to share another congratulatory message aimed at the couple.

She wrote: "Congratulations @justinbieber Hailey! I love you forever, baby Jack!"

The 'Baby' hitmaker confirmed the news that he had become a dad with a snap of the newborn's foot held by his mom.

He captioned the picture: "WELCOME HOME. JACK BLUES BIEBER."

The Rhode Skin founder and the 'Sorry' singer announced in early May that they were expecting a child - and revealed Hailey was six months along at the time, making her due date sometime in early August.

Hailey didn't announce their big news until she was six months pregnant as she was able to hide her small bump using "big jackets".

She told W magazine: "I was honestly able to keep it quiet because I stayed small for a long time. I didn't have a belly, really, until I was six months pregnant, which was when I announced it. I was able to wear big jackets and stuff."

Hailey went on to admit she "probably could have" kept the pregnancy a secret all the way through to the birth, but she didn't like keeping such big news quiet.

She added: "I probably could have hid it until the end. But I didn't enjoy the stress of not being able to enjoy my pregnancy outwardly. I felt like I was hiding this big secret, and it didn't feel good. I wanted the freedom to go out and live my life."