Taking to Instagram on Saturday, February 02, Lily, 33, announced that she had given birth to a son, a sibling for her six-year-old daughter Dixie, last Tuesday.
Alongside a black-and-white photo of her baby's tiny feet, she wrote, "Winston Roy Followill. Blessed our lives January 29, 2019."
Neither Lily nor her husband Caleb have shared any further details, although a number of the couple's celebrity friends were quick to add congratulatory comments to the post.
"Congrats Lily!!" wrote Kate Bosworth, alongside a series of kiss face emojis, Chrissy Teigen commented, "TOESSSSSS (sic)!!!!!! Congratulations," and Diane Kruger added, "Congratulations. A miracle every time."
Meanwhile, Lily's friend and Victoria's Secret colleague Candice Swanepoel simply posted a string of blue heart emojis.
🖤 Winston Roy Followill 🖤— Lily Aldridge (@LilyAldridge) 2 February 2019
Blessed our lives January 29, 2019 https://t.co/7moKlH46dg
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So proud to walk the @brandonmaxwell runway pregnant! I’ve walked a few runways in my life and this is a moment that I’ll look back on forever with great emotion ❤️ Thank you Brandon for letting my shine & being such a true gentleman, Love you FOREVER!!! Thank you @georgecortina for making me feel so beautiful 💋 makeup by my love @tompecheux & hair by the sweetest @jamespecis ⚡️ @mr_stephengalloway from pumping me up before the runway 💃🏽 And love to all the amazing powerful girls casted in the show by @johndavidpfeiffer 💋 It was so much fun being backstage will all the girls, everyone was so uplifting and rubbing my belly celebrating this beautiful journey with me 🤰🏻 Nothing but Empowerment at Brandon Maxwell❤️❤️❤️❤️
Back in August (18), Lily confirmed her pregnancy by sharing a photo on Instagram showing her posing on a beach in a bikini, with her burgeoning bump on full display. The brunette beauty did not reveal her baby's gender or due date at the time.
However, she has remained very active throughout her pregnancy, and walked the runway at Brandon Maxwell's show during New York Fashion Week in September.
In a post thanking the designer for casting her in the presentation, she wrote on Instagram, "So proud to walk the @brandonmaxwell runway 5 months pregnant! I've walked (a) few runways in my life and this is a moment that I'll look back on forever with great emotion. Thank you, Brandon, for letting my shine & being such a true gentleman, Love you FOREVER!!!"
Caleb, 37, and Lily married in 2011.