Hilaria Baldwin has introduced her son Romeo to the world.

The 34-year-old fitness and wellness expert took to Instagram to share the first picture of the most recent addition to her and Alec Baldwin's family.

She captioned the sweet picture of baby Romeo: ''We are happy to introduce you to Romeo Alejandro David Baldwin.''

Hilaria gave birth to Romeo - her fourth child - earlier this week.

In an Instagram post, which showed the new parents gazing down at their tiny tot, Hilaria wrote: ''He's here! He's perfect! 8lbs 2oz #wegotthis2018 (sic)''

Whilst Alec posted the same picture on his own Instagram account, and captioned it: ''Here we go again! #BaldwinitosEverywhere (sic)''

The couple, who married in 2012, are already the proud parents of daughter Carmen, four, son Rafael, two, and 20-month-old son Leonardo, whilst Alec has 22-year-old daughter Ireland from a previous relationship.

The arrival of the couple's fourth child will no doubt be good news to young daughter Carmen, as Hilaria previously revealed the toddler is already keen for her parents to have yet another baby, as she wants a little sister.

Hilaria said: ''Mommy doesn't even want to think about another one right now. But we'll see if she [Carmen] bullies me into it.''

The pair waited for a few days to see what monikers suited their little one before deciding on his final name.

Hilaria shared previously: ''This is the first one that we really don't know going into it, and we're going to see what he looks like and take a good look.''