Alec and Hilaria Baldwin's fourth child, son Romeo Alejandro David, was born Thursday, May 17

The newest Baldwinito has a name.

Hilaria Baldwin officially introduced her fourth child and third son to Instagram Monday, showing her baby boy lounging on his mama’s lap.

The newborn looks content in a long-sleeved white onesie, fast asleep as Hilaria’s left hand — still adorned with a hospital bracelet — supports his head.

“We are happy to introduce you to Romeo Alejandro David Baldwin 💛” the 34-year-old wrote of herself and husband Alec Baldwin.

Want all the latest pregnancy and birth announcements, plus celebrity mom blogs? Click here to get those and more in the PEOPLE Babies newsletter.

The couple announced Romeo’s birth on Thursday, with the fitness instructor captioning a hospital photo of herself and Alec, 60, “He’s here! He’s perfect! 8lbs 2oz 💛 #wegotthis2018.”

RELATED VIDEO: Hilaria Baldwin Shares Hilarious Snap After Family Photo with Santa Didn’t Turn Out as Planned

The new addition joins siblings Leonardo Ángel Charles, 20 months, Rafael Thomas, 3 next month, and Carmen Gabriela, 4½. Alec is also dad to 22-year-old daughter Ireland Baldwin, from his previous marriage to Kim Basinger.

The new mom of four got candid on Instagram Sunday, sharing a mirror selfie taken in her underwear less than a day after giving birth, plus snaps to her Instagram Story taken around the same time after delivering her two older sons.

“I always post a photo in this mirror in my hospital room within 24 hours after having my babies (except with [daughter Carmen Gabriela, 4½] … I was too much of a nervous first time mama 😂) … I took this photo, Friday, the morning after this new baby was born,” wrote Hilaria.

“My purpose here is to normalize the postpartum figure and over the next days, weeks, and months, show you how I strengthen my body and return to my non pregnant self,” explained the yoga pro. “You all came with me through my pregnancy … now it’s time to turn back into me.”