Alec Baldwin and his wife Hilaria Thomas at the 2015 Elton John AIDS Foundation Oscar Party in West Hollywood, California on February 22, 2015.

Alec Baldwin and his wife Hilaria have welcomed a baby boy into the world.

The 57-year-old actor's 31-year-old yoga instructor wife has announced the birth of their son Rafael Thomas on Instagram, posting a picture of the baby's tiny hand on the photo-sharing website.

She captioned the image: "We are happy to announce the birth of Rafael Thomas Baldwin."

The birth comes 22 months after the couple - who tied the knot in 2012 - welcomed their first child, a daughter named Carmen.

Hilaria documented this pregnancy by posting pictures of her growing bump on the photo-sharing website and keeping fans updated on her progress.

However, the impending birth has not stopped Hilaria from continuing with her busy lifestyle, which has recently included penning a fitness and wellness book.

Meanwhile, Alec - who already has a 19-year-old daughter, model Ireland, from his marriage to actress Kim Basinger - revealed earlier this year just how much he was looking forward to the birth of his baby boy.

He said: "(I'm) blessed, very blessed. We're having the baby and that's almost surreal to me."

Hilaria also admitted she was thrilled Carmen will have a brother close to her age.

She said: "We're really excited to have another baby! We definitely wanted Carmen to have a sibling near her age."

Bang Showbiz