Maxwell! Boomer! Birdie! See Which Celeb Babies Celebrate Their Birthdays in May

MAXWELL JOHNSON

Jessica Simpson's daughter Maxwell Drew — who turned 6 on May 1 — rewrote the stars in costume as The Greatest Showman's Anne Wheeler during her circus-themed birthday bash.

"🎪 Maxwell's Over-The-Top Big Top 🎪 #TheGreatestShowman #MAXIDREW #6," the singer captioned a family photo of the foursome at the event.

BOOMER PHELPS

Although he has big-brother duties to tend to since the Feb. 12 birth of Beckett Richard, Michael Phelps' older son Boomer Robert was the star of the show for his second birthday on May 5.

"Happy bday @boomerrphelps !! I love you so much little man … may this be your best 2nd bday your heart dreamt of!" the swimmer wrote alongside a picture of the birthday boy smiling while playfully holding onto his dad's chin.

GREYSON MATHEWS

Happy birthday, Greyson Valor! Just like Boomer, the younger child of Jenni "JWoww" Farley and husband Roger Mathews turned 2 on May 5.

"#Freeeeeeeeeeeeeeedom!!!!!!!!!!!" Mathews jokingly captioned a video of the birthday boy playing with the figures that were atop his cake, paying no attention to his parents as they liken his cake-smeared visage to the face paint worn by William Wallace in Braveheart.

JAXON CUTLER

Kristin Cavallari's middle child Jaxon Wyatt celebrated his fourth birthday on May 7 with a huge gold balloon shaped like the number "4."

"Happy 4th birthday to my little baby bull, Jaxon," the reality star captioned a tribute photo. "He brightens up my life every single day and makes me laugh more than anyone I know 💙"

LAIRD STONE

Laird Vonne is officially a teenager! Sharon Stone's middle son turned 13 on May 7.

His mom marked the occasion with a sweet birthday photo on Instagram, showing Laird gazing down at "1" and "3" candles atop two delectable-looking cupcakes.

NOAH MAZUR

Noah Phoenix is 6! The adorable youngster donned a ninja outfit for his birthday festivities, with model mama Alessandra Ambrosio sharing sweet photos from the day.

"Happy birthday to you my love ... may all your dreams come true 🎉🎂💙🍭💕😘🎈💫," she wrote on May 7 to accompany a group photograph that also included Noah's big sister Anja Louise, 9½.

BIRDIE DANIELSON

WWE power couple Brie Bella and Daniel Bryan's baby girl Birdie Joe is already 1, celebrating her very first birthday on May 9 with her parents — and a fistful of cake!

"And so sassiness begins!!! 💕 #BirthdayGirl #mygirl #bird," Bella captioned a photo of her daughter in a tutu and a shirt that reads, "I'm ONE Today!"

AXTON HALEN

"My Godzilla monster turns 1 today," Mia Tyler captioned a throwback hospital photo of herself and son Axton Joseph on May 10.

"Everyone said it would go by fast and it sure has been a flash," she added. "He's changed every molecule in me to pure love. I'm forever grateful."

RYAN ROSENBERG

Ryan Ava Erhard's last birthday as an only child was filled with all things princess.

"Some very special guests came to help Ryan celebrate her birthday! #This is 3 👑," second-time mom-to-be Haylie Duff wrote of her daughter, whose big day was May 11.

APPLE MARTIN

During a rare appearance on Gwyneth Paltrow's Instagram account, birthday girl Apple Blythe Alison looked like the spitting image of her mom as she hit her golden birthday on May 14.

"Happy birthday, my darling girl. You make every day feel like Christmas morning," the actress and Goop founder wrote alongside the post. "You are the most vibrant, hilarious, twirling all over the place, beautiful (inside and out) young woman."

She added of her older child with ex Chris Martin, "You are an amazing thinker and an incredible songwriter. Thanks for still hanging out with me, even though you are 14."

ALIJAH BASKETT

On May 16, Kendra Wilkinson and ex Hank Baskett's younger child, daughter Alijah Mary, turned 4.

"Happy 4th bday my sweet angel Alijah," Wilkinson wrote to accompany a memorable photograph of her younger child dressed in unicorn splendor and holding a bunch of colorful balloons.

Added the star, "Just like mama, she's here on earth to celebrate life at all times."

STORY GOLDBERG

"Happy happy 2nd birthday to my sweet Story," mom of four Soleil Moon Frye wrote alongside a mother-son snap in honor of her youngest child's May 16 milestone.

She continued, "You are such a love. I want to hug you for hours, cuddle you for days and hold on to every moment with you. You are so many chapters to this incredible journey & I love you madly from the bottom of my heart."

FUTURE WILBURN

Happy birthday, Future Zahir! On May 19, Ciara shared a snapshot of herself and her newly minted 4-year-old sporting matching sunglasses, headphones and smiles as they gave the camera a thumbs up.

"#HappyBirthday My Little Prince!" wrote the singer. "You are everything I've hoped for and more! I can't wait to see you take 4 by storm! I love you soooooo much!"

EMERSON SWISHER

The big 5! Nick and JoAnna Garcia Swisher's first child, daughter Emerson Jay, celebrated on May 21.

"Happy Birthday to our perfect mix of sugar and spice," JoAnna captioned a sweet photo gallery featuring the birthday girl. "Emme Jay, you amaze me everyday with your imagination, kind heart, and wit."

She continued, "I love you more than I could ever describe and I'm so proud and thankful to be your mommy! Love you, champ!"

MCCOY PORTER

Lucky McCoy Lee got to celebrate his May 23 birthday at the Happiest Place on Earth!

"Bubba's big 3rd Birthday gift was a day at #Disneyland with Mommy and Daddy ... or was it a gift for us?" Scott Porter joked, sharing a photo of himself, wife Kelsey and little McCoy in front of Sleeping Beauty Castle.

KINGSTON ROSSDALE

Kingston James McGregor is already just year away from becoming a teenager! The oldest of Gwen Stefani and ex Gavin Rossdale's three sons is 12 as of May 26.

Wrote Stefani next to a throwback photo of Kingston in a Spider-Man costume, "My baby is 12 years old #kingjames gx 😭 #iloveyouking"

WESLIE FOWLER

Another May 26 birthday? Allison Holker's daughter Weslie Renae, who hit double digits this year.

"HAPPY BIRTHDAY @weslierboss ! I don't even know where to begin with explaining the love I have for my daughter," the dancer and proud mom captioned a beautiful black-and-white image of Weslie.

She added, "Weslie you are majestic! She is kind, caring, and wise beyond all belief!! She turned 10 today and I am honored to call myself your mother."