It's a Girl! Hailey Baldwin's Sister Alaia Welcomes Daughter Iris Elle: 'Absolutely Perfect'

The Baldwin clan just got a little bigger!

Alaia Baldwin welcomed her first child with husband Andrew Aronow on Monday, Aug. 17, she announced on Instagram late Wednesday evening.

"IRIS ELLE ARONOW! 💞Born on 8/17/2020, 6lbs 11oz. She is absolutely perfect, we are all happy and healthy," wrote Alaia, 27, going on to thank her doctor "for making our experience go as smoothly and as beautifully as I ever could have imagined."

"We couldn't be more thrilled to finally meet you," proud dad Aronow added in his own post, sharing the same snapshots of the couple in the hospital with their daughter and Alaia's doctor.

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Alaia is the daughter of actor Stephen Baldwin and the older sister of Hailey Bieber. And the model, 23, is more than ready to spoil Iris, too.

"Been hard to keep this to myself, my beautiful niece is here and she is PERFECT. Auntie Hails loves you sooooo much," Hailey wrote on her Instagram story Wednesday.

Alaia — who wed Aronow in 2017 in a stunning outdoor ceremony in her native New York — announced her pregnancy back in April. "I made something extra special for @andrewaronow's birthday this year," the then-mom-to-be captioned a sweet back-and-white Instagram photo of Aronow kissing her growing baby bump.

Hailey chimed in with her excitement over the happy news, commenting on the post, "My niece" and "Screaming!!!!" before sharing the photo to her own Instagram Story. "I'm gonna be an Aunty!!!!!!!" she exclaimed.

RELATED VIDEO: Hailey Baldwin Says That She and Husband Justin Bieber "Haven't Made Any Babies" in Quarantine

As for starting her own family, both Hailey and her husband Justin Bieber have said they want to wait a bit before taking that next step.

"We didn't make any babies, so that's that," Hailey said earlier this month of the couple's quarantine activities during PaleyFest LA, where the duo promoted Bieber's latest project, Justin Bieber: Seasons.

In February, the Canadian "Yummy" singer, 26, told Apple Music's Zane Lowe that he wasn't planning on becoming a father anytime soon.

"I want to start my own family in due time," Bieber shared with Lowe. "I want to enjoy being married for a little bit, go on tour, be married, enjoy traveling with just us, build more of our relationship. I think that it's definitely the next step, for sure."