Mötley Crüe bassist Nikki Sixx's wife Courtney celebrated their daughter on the way in May with a flower-filled, Beatrix Potter-themed baby shower

Nikki Sixx has a new roadie!

On Saturday, July 27, the Mötley Crüe bassist’s wife Courtney gave birth to his fifth child and their first together — a baby girl named Ruby Sixx, the new parents shared on Instagram early Wednesday morning alongside a photo of an elegant white baby carriage filled with pink flowers.

The proud dad, 60, described the new addition as “a spunky little girl with a full head of hair” in his post, praising his wife for being “a real natural as a mom” and sharing that they “are already sleep training her with a metronome and I got her a pink bass.”

Courtney, 33, revealed that she was in labor for 18 hours but gave birth during “a very quick delivery,” raving that her baby girl is “more precious and more beautiful than I ever could have imagined.”

“My heart just melted and I was instantly head over heels in love as my life changed forever in an instant. I never knew this kind of love existed,” the new mom added of the moment she held Ruby for the first time.

Nikki and Courtney Sixx
| Credit: Chelsea Lauren/WireImage

While Ruby is Courtney’s first child, Nikki (whose given name is Frank Carlton Serafino Feranna, Jr.) is also dad to Frankie-Jean Mary, 18, Decker Nilsson, 24, Storm Brieann, 25, and Gunner Nicholas, 28.

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Courtney and Nikki announced they were expecting their first child together in January, almost five years after tying the knot at Greystone Mansion in Los Angeles in front of 130 guests.

“What a great way to start off 2019 for Courtney and me,” Nikki told PEOPLE at the time. “I am so excited knowing that I’m not going to be touring during the pregnancy, which makes it even more special.”

“We have been talking about having a baby since we met and were married almost five years ago. It’s definitely been on my mind every day,” explained Courtney. “We are beyond thrilled to be bringing a little Sixx into the world and I know we will make amazing parents together.”

It has been almost two decades since the rocker last became a dad, and this baby is on the way despite the bassist having previously had a vasectomy.

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Courtney was honored at a flower-filled, Beatrix Potter-themed baby shower in May, and the How2Girl expert shared photos from the special day exclusively with PEOPLE.

“I collaborated with Mark’s Garden on the floral designs, incorporating storybooks into all the décor,” she explained of the event’s inspiration. “They started searching for the perfect vintage books six months ago. My nursery also has vintage prints of Beatrix Potter, so I thought it was a perfect fit!”

Among the then-mom-to-be’s 50 guests were famous faces like Alison Eastwood, Tanisha Harper and Real Housewives of Orange County alums Heather Dubrow and Gretchen Rossi — the latter of whom was also expecting her first child, a baby girl, at the time — as well as Brittany Furlan Lee, who married Nikki’s bandmate Tommy Lee in February.

The DIY expert also revealed her baby girl’s first name to PEOPLE, and shared that she was eagerly anticipating spending time with the newborn: “I’m so excited for so many things like dressing her, teaching her, creating things with her and just like my mom said at my shower, holding my future best friend in my arms.”