"Carmen is decorating her baby brother ❤🧡💛💚💙💜💖😂," Hilaria Baldwin captioned a belly-baring photo of herself in a black bra and panties
The adorable 4½-year-old is completely enthralled in a new snap shared to her mama’s Instagram account, covering Hilaria’s bare baby belly in a variety of colorful heart-shaped stickers.
In the sweet mirror selfie, the mom-to-be is wearing only a black bra and panties (both Heidi Klum Intimates) as her daughter busies herself “decorating her baby brother.”
“Hello 3rd trimester!” Hilaria, 34, captioned the Saturday post.
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“Every single time I do this, I can’t believe the elasticity of the human body,” wrote the fitness guru on her Saturday photo. “It’s hard, and I get tired (especially with 3 on the outside), but I feel so lucky to have experienced this in my life.”
Hilaria opened up to PEOPLE in November about her growing family, admitting she “never knew how many kids” she wanted, but “really, really” likes motherhood and is “excited” about her upcoming new addition.
“We were like, ‘Oh, should we have another kid?’ ” she recalled of her conversation with Alec, 59. “We were like, ‘You know what? Let’s try something different — let’s try.’ [With] the other ones, it’s not like we were like, ‘Oh my God, how did this happen?’ But this is the only one we [planned].”