Anna Duggar is pregnant with a baby girl.

The 30-year-old announced the sex of her unborn sixth child with husband Josh Duggar in an Instagram post Thursday.

Anna enlisted the help of her kids, Mackynzie, 9, Michael, 7, Marcus, 5, Meredith, 3, and Mason, 19 months, to share the news.

She posted a video of Marcus pouring vinegar in a beehive-shaped object that spewed pink foam.

"It's a girl!" the kids excitedly exclaim.

Anna confirmed the news and reflected on her first "gender reveal" in the caption.

"This is the 6th gender reveal for our little family and it's always so exciting! Each child God has given us is unique and special -- we all look forward to the arrival of our daughter/sister this fall!" she wrote.

Anna said Josh's sister Jessa Duggar reminded her about her first gender reveal on "Today" in 2010, which featured a cake from "Cake Boss" star Buddy Valastro.

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Anna also reflected on the death of "Grandma" Mary Duggar, the mother of Josh's father, Jim Bob Duggar.

"A little behind the scenes story: When I was expecting Kynzie, Grandma Duggar excitedly told me of a 'new trend' that featured baking a gender reveal cake. Grandma asked if she and Amy could bake one for us?!?! Josh and I loved the idea and that was our plan... until our producers heard about the idea and it grew quite a bit!" Anna recalled.

"Buddy the Cake Boss ended up baking the first gender reveal cake for us!"

"With Grandma's passing last week, this 6th gender reveal is a reminder of her love -- I'm so glad we were able to share the news of our third little girl with Great-Grandma before she went to be with Jesus! #littleduggars," she added.

Mary died June 9 at age 78.

Her cause of death was confirmed last week to be an accidental drowning in her pool at home.

The Duggars came to fame on the TLC series "19 Kids & Counting."

The show was canceled following Josh's sexual abuse scandal in 2015, and the family, sans Josh, now stars on the series "Counting On."