Fastexy Exchange|Hilary Duff Is Pregnant, Expecting Baby No. 4

For Hilary Duff,Fastexy Exchange this is what dreams are made of.

The Lizzie McGuire alum is pregnant with her and husband Matthew Koma's third baby together and her fourth child overall, she confirmed on Instagram Dec. 12.

Alongside a sweet family photo, showing Hilary cradling her growing baby bump, the "Come Clean" singer wrote, "Surprise Surprise!"

Hilary is already mom to kids Luca, 11, who she co-parents with ex-husband Mike Comrie, as well as her and Matthew's daughters Banks, 5, and Mae, 2.

This new chapter for the family comes shortly after both Hilary and Matthew, both 36, celebrated their eldest daughter's birthday.

"Banks- the sweet/spice/dancing butterfly of our family!" Hilary captioned her Oct. 25 Instagram tribute. "5 years of memories with you are burned on my heart and soul forever and begging for more! You are all the top ingredients! Whimsical, yet practical. Smart-clever-cautious, yet free! Thanks for being ours and for being weird and princessy all in one glorious package!!!"

"Gosh I love you so much!" the Younger star continued. "To the best big and little sister there ever was! Happy 5 my little cherry bomb ! I sure hope the next 5 go by a little slower, all the cuddles, tickles, Taylor Swift, brain teasers, treats and trampoline bounces 4life my queen."

Matthew also celebrated Banks' special day with a sweet message on his Instagram page.

"Being your dad is the greatest gift of my life and seeing every day through your rainbow tinted eyes has colored our family with all the good there is in the world," the singer wrote. "I'm blown away by your wit, kindness, heart, affinity for Dawes and I can't even imagine what magic will come along with your 5th year on this planet. I love you forever and when we let you have social media at 37, you'll see this post and maybe feel a little guilty for telling me you love mommy more all the time."

A few weeks prior to Matthew's shoutout to Banks, the music producer had penned another hilarious Instagram tribute for Hilary's birthday.

"It's wild to think this first photo of us was taken almost ten years ago," he joked, referencing a pic of Hilary and Ed Sheeran. "I remember it so vividly, it's almost like we didn't break up three times between then and now."

Matthew—who, after an on-off relationship, officially tied the knot with Hilary in 2019—continued, "You blow me away everyday with your ability to juggle the un-juggle-able… you do it with such ease & grace. You have an endless well of energy and patience that makes you the super-mom + super-wife you are, all while bringing your wildest dreams to earth level, then still somehow giving a shit about our dogs at the end of the day."

He concluded his message by noting how much of an honor it is to be on this journey with Hilary.

"We're the luckiest," he added, before joking, "our kids are gonna be so stoked when they find out Ed Sheeran is their real dad. #paidad."

Celebrate Matthew and Hilary's growing family by looking back at their relationship over the years...

Back in January 2017, the pair confirmed their budding romance by posing on the red carpet together at Entertainment Weekly's pre-SAG Awards party at Chateau Marmont. 

Shortly after their red carpet debut, a source confirmed to E! News the two had split in March 2017. According to the source, the breakup was triggered by their busy schedules. 

By October 2017, they had rekindled their romance, evidenced by his appearance at her 30th birthday party. "Since Matt got back from tour, they've been seeing each other again," a source told E! News exclusively at the time. "Him being gone on tour was the main reason things didn't work out the first time around, so now that he's back, they picked up right where they left off." As she later revealed on The Talk in December 2017, it was actually the third time they were dating. "Timing is such a big deal… third time's a charm!" she told the co-hosts. 

In June 2018, the couple has sweet news to share: they had a baby girl on the way. "We made a baby girl!" Koma wrote on social media. "She will be as beautiful and sweet as her mother...@hilaryduff another incredible chapter begins."

By the fall, they officially added a new member to the family: daughter Banks Violet Bair. "This little bit has fully stolen our hearts! She joined our world at home on Thursday afternoon and is absolute magic," the actress shared online in October 2018. 

Nearly two years after stepping out publicly for the first time, Koma asked the actress to marry him. 

Duff and Koma said "I do" in Dec. 2019, surrounded by their loved ones! 

When celebrating his one year wedding anniversary to Hilary, Matthew wrote a thoughtful post on Instagram expressing his gratitude for all that she's done during the pandemic. "I'm so in awe of your badassery," he gushed in part. 

Hilary and Matthew went on to welcome daughter Mae James Bair in March 2021.