Nicky Hilton Rothschild welcomed her third baby with her husband James Rothschild.

The 38-year-old businesswoman took to Instagram on Tuesday to share a sweet photo featuring herself when she was pregnant and James standing near the window.

"We are officially a party of 5! Welcome to the world sweet boy," Nicky captioned the photo. "Mom, dad and big sisters could not be more smitten."

Celebs and fans took to the comments section to share their congratulatory messages.

Actress Crystal Kung Minkoff wrote, "Congratulations" with a heart emoji while actor Donald Faison's wife CaCee Cobb commented, "So happy for you!!!!!" Model Cheyenne Tozzi wrote, "Congratulations guys sending so much love."

Nicky flaunted her baby bump on Instagram a week prior and wrote, "Patiently waiting on your arrival."

Nicky also shared a series of photos from her baby shower, featuring her sister Paris Hilton and mother Kathy Hilton. "Showered with so much love at baby boy’s sprinkle," she wrote on Instagram at that time.

During an interview earlier this year, Nicky revealed that her mother doesn't want to learn about her third baby's sex ahead of the birth. "My mom's very old-fashioned. She's like, 'I didn't find out for any of you kids. Please, it's the ultimate surprise in life, do not find out,'" she said.

However, she did know the sex of the baby before giving birth to her first baby girl as the baby shower's venue was decorated with a pink and white theme. For the second baby, she kept it a secret as she threw a baby shower with a blue and pink theme.

Nicky and James got married at Kensington Palace in England in 2015. The couple already has two daughters, Lily-Grace Victoria, 5, and Theodora "Teddy" Marilyn, 4.

On the work front, Nicky appeared in the TV series "The Real Housewives of Beverly Hills" from 2015 to 2021. She also appeared in the TV series "Fashion News Live (Vintage)" from 2016 to 2018. Nicky also made a guest appearance on her sister's cooking show, "Cooking with Paris."

She also appeared in the movies like "Pauly Shore Is Dead," "Wishman" and "Pledge This!"

Nicky Hilton James Rothschild
41. Nicky Hilton and James Rothschild: While its unclear what the exact total was for the Hilton heiress' wedding to her banker husband in 2015, it is known the price tag was in the multimillions. The couple married at Kensington Palace—a.k.a. the same grounds where Prince William and Kate Middleton and Prince Harry and Meghan Markle reside—which isn't a cheap venue. The couple is pictured attending the Animal Haven 50th Anniversary Gala in New York City on June 14, 2017. Rob Kim/Getty Images for Animal Haven