Tennessee! Giovanna! Preston and Jayden! See Which Celeb Babies Celebrate Their Birthdays in September

50 Cent and ex Daphne Joy went big for the second year in a row to celebrate their son Sire's birthday. Last year's theme? Teen Titans Go! This year? A slime-filled pool party.

"My baby getting BIG, 5 years went so fast man," 50 Cent captioned a sweet Instagram snap from the party, showing him kissing Sire on the cheek.

"He looks at me like I'm a super hero so I gotta do better," the rapper added of his son, whose birthday is Sept. 1.

Happy birthday, Romeo James! The second-born of David and Victoria Beckham's four children is 15 as of Sept. 1.

"Happy 15th Birthday big boy," the proud dad captioned a photo of himself and Romeo on a hike. "Fine young man growing up to be a fine young gentleman but has only beaten his dad at tennis just the once 🎾 so far but maybe now he is 15 that's gonna change 😳"

He added, "Happy Birthday big boy we love you... @romeobeckham@victoriabeckham." 

It was a big day for Spice Girls alum Mel B's youngest daughter Madison on Sept. 1 — she turned 6 and started "big girls school" the same day!

"Happy birthday my sweet baby girl,you are my world my shinning star my everything," she wrote on Instagram next to a photo of the pair.

"I just cannot believe today your 6 AND your starting big girls school sooo much in one day wowza ❤️💗💙"

"Tomorrow my baby girl celebrates her first birthday. Wow...my heart is full," Lacey Chabert captioned a photo of herself with daughter Julia Mimi Bella, whose birthday is Sept. 1.

"Thank you God for allowing me to experience this kind of love," added the Mean Girls star.

Jessie James Decker and Eric Decker's younger child is 2! Eric Thomas II — whom Jessie affectionately calls "Bubby" — celebrates on Sept. 3.

"Happy happy happy birthday to my beautiful, sweet, tender hearted, quirky, tough, emotional, happy, affectionate baby boy Eric aka Bubby," Jessie captioned a pro photo series from her baby boy's first moments.

"Mommy loves you so much and I thank God every day he chose me as your mommy," she added. "You fill my heart all the way up sweet baby. Happy 2nd birthday Bubs. I hope when you're 20 you still wanna snuggle and smooch on your mama 😂😩"

Big-brother-to-be Cash Van took a bite out of life this month, turning 3 on Sept. 7 with a two-tier, shark-themed confection.

"Happy 3rd birthday to our adventurous little man Cash!!!" Lady Antebellum's Dave Haywood captioned an Instagram snap.

"He was so excited to blow out HIS candles on HIS cake!! 🎂Love you buddy!!!!!" added Haywood, who is currently expecting a daughter with wife Kelli.

"Not pictured: 14 meltdowns," Dave Annable joked on Instagram next to a photo of his daughter with wife Odette Annable: Charlie Mae, who's 2 on Sept. 7.

"#happybirthdaymylove #disneyland," the actor hashtagged the cute black-and-white snap.

Mother of four Jessica Capshaw celebrates her oldest child (and only son) Luke Hudson's 10th birthday on Sept. 8.

"A epic trip to celebrate 10 years of this young man's life," dad Christopher Gavigan captioned a lakeside photo of the couple with their son.

"Happy BDay LHG - it's an honor & absolute pleasure to be your Dad!" he added.

Jordana Brewster's older son Julian is 4 as of Sept. 10 — and it looks like the little guy might already have his future career picked out.

"Happy Birthday my Julian," the actress wrote to accompany a precious shot of Julian decked out in kids' firefighter attire.

Britney Spears and Kevin Federline's younger son Jayden James turned 11 on Sept. 12, marking the occasion with not one but two celebrations — one of which was a surprise party at home for himself and brother Sean Preston, who turned 12 two days later.

"After a wonderful trip to @disneyland with their friends, we had a small surprise party at home with lots of gifts! 🎉🎁❤️," Spears captioned a hilarious Instagram clip, showing Jayden rolling around on the floor with excitement.

Alec and Hilaria Baldwin's baby boy Leonardo Ángel Charles is 1! The youngest child of the actor and fitness guru has his first birthday on Sept. 12.

"It's my wife's boyfriend's first birthday..." Alec joked in the caption of a sweet photo montage dedicated to Leo.

Another Sept. 12 birthday? Nick and Vanessa Lachey's oldest child Camden John, who's turning 5 years old.

"And just like that my sweet angel boy is 5 years old! 😩" Vanessa captioned a gorgeous, sunny shot of her little man. "I took this picture as the sun was setting and I got teary eyed looking at him because he looks so grown up."

"5 years ago today at 6:54pm I became a Mother and it's one of the BEST things that has ever happened to me!" she added. "I Love You, Bubba!"

Alongside his brother Jayden, Sean Preston is celebrating his birthday in September — the 14th to Jayden's 12th, turning 12 years old.

"So much fun celebrating the boys' birthdays at @disneyland yesterday!!!" Britney Spears captioned a photo collage of the boys enjoying the park with six of their pals.

"Since my life really began with her, I guess I turn 2 at midnight," Chance the Rapper captioned a too-cute photo of himself and Kensli, whose birthday is Sept. 15.

"TURN UPPPP FOR MY DAUGHTER 💥🎁🎂🎂," he continued.

Sept. 16 is the 1st birthday of fourth-time mom-to-be Emily Maynard Johnson's current littlest household member, son Gibson Kyle.

"Happy 1st Birthday to my sweet Gibson!" the former Bachelorette wrote on Instagram alongside a gallery of photos chronicling her baby boy's first year of life.

"Thank you for being the cutest, happiest baby on the planet and taking it easy on your mommy," she wrote. "We love you all the way to heaven!"

Naya Rivera's mini-me son Josey Hollis turns 2 on Sept. 17 - and dad Ryan Dorsey shared the perfect photo post to wish his little guy a happy birthday.

"Est. 2015. And then the sweetest boy was II. #Love," he wrote. "Hello #terrificTwos (being optimistic). Happy Birthday Josey boy ! We love you!!"

It's double digits for Valentina Paloma! The daughter of Salma Hayek and husband François-Henri Pinault is 10 on Sept. 20.

"Happy birthday Valentina! I'm so grateful for the decade of love you brought to our lives," Hayek wrote on Instagram in English and Spanish, captioning an adorable throwback clip of a toddler Valentina playing a tiny piano and requesting that her mom sing along.

Olivia is 7! Kimberly and James Van Der Beek's oldest child celebrates her birthday Sept. 25 — and she had quite the festive day, as evidenced by her parents' Instagram accounts.

A post on Kimberly's account showed Olivia basking in the glow of candlelight, while James' Instagram story even chronicled the little girl helping her dad build her own dollhouse.

"7 years ago today, I finally got to meet a sweet little soul I'd been missing my whole life... and didn't even know it," the father of four captioned a gallery of himself with Olivia over the years, starting with her birth.

"Olivia, I am honored to know you and get to watch you grow and evolve and come into yourself and outsmart me and astound me and make me laugh every day," he added. "I've often said I never feel like kids are 'ours'  — they are their own, and we just get to be there while they reveal themselves. I had to wait 33 years for the privilege ... but boy are you ever worth it, kiddo."

Lukas Graham frontman Lukas Forchhammer's first child, daughter Viola, is already 1 on Sept. 25.

"Happy birthday 🎈🎉🎂🎁," the "7 Years" singer's longtime love Marie-Louise "Rillo" Schwartz Petersen wrote alongside a cute snap of their baby girl standing up.

Nicole "Snooki" Polizzi's younger child Giovanna Marie is 3! The adorable little girl and her 5-year-old big brother Lorenzo Dominic regularly star on their mom's Instagram account, but the cute gallery the Jersey Shore alum shared on Sept. 26 might take the (birthday) cake.

"Happy 3rd birthday to my baby, mini me, best friend, spirit animal," Polizzi captioned the series, showing her little girl hamming it up in a dress emblazoned with a gold-crown graphic that reads "Three."

"So lucky to be your mommy & so proud of the wonderful, silly, adorable little girl you have become," she added. "Now stop growing and stay this age forever. 😩😩😩😩😩 #Crying #StopGrowing #JesusHelpMe #INeedATranquilizer."

"Charlotte is now 3! Best part of my life is being her & Aidan's mom," mother of two Chelsea Clinton captioned a cute Twitter photo on Sept. 26 to wish her daughter a happy birthday. (Clinton and husband Marc Mezvinsky's son Aidan celebrated his 1st birthday June.)

The snap showed a huge number "3" metallic balloon, with a large giraffe-shaped balloon and a smaller red one with stars in the background.

Happy birthday, Tennessee James! Reese Witherspoon's little man turns 5 this month, with the actress using Instagram on Sept. 26 to shower him with affection.

"Happy Birthday to my littlest guy , Tennessee! 🌈☀️," Witherspoon captioned the cute shot of the birthday boy holding up a huge, colorful "5" balloon.

"Everyday you bring us so much joy with your sweet smile and beautiful laugh," she added. "I love you so much! 🎉 #feeling5 #HBD"

Soon-to-be big brother Hank is 2! The son of Andy Roddick and Brooklyn Decker is gearing up to welcome a baby sister soon.

"Hank's main concern is how the 'baby is going to climb out of the tunnel,' " Decker told PEOPLE this month of her son, whose birthday is Sept. 30.