Guidolin, 26, posed in the buff for a series of black-and-white pregnancy photos while 32 weeks along with twin baby girls.
In some photos, the nutritionist and model dons lacy matching lingerie, and in others her hands cover her bare breasts.
Guidolin, who already has two little boys, shared one of the images through her Instagram on Thursday.
"The babies currently weigh 3kilos (6p6oz) (combined)," she wrote.
Guidolin, who continued to weight train throughout her second pregnancy, operates her own website where she sells in-depth exercise and nutrition plan programs, as well as her several recipe books.
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The mom hasn't been shy about documenting her pregnancy through social media, often sharing photos in underwear or tight-fitting workout gear.
On Friday, Guidolin posted a date night pic, writing that she's gained 33 pounds with her baby girls.
"I have gained 15 kilos so far, and am expecting the weight to increase pretty quickly these last few weeks. I just cannot wait to meet these baby twins," she wrote.
Finally date night with the husband after a CRAZY week moving into our new gym! We haven't had a nice dinner just the 2 of us for a while, and with only weeks left of my pregnancy- We are taking full advantage of these pleasures!! By the end of the day, my entire body is starting to ache I have gained 15 kilos so far, and am expecting the weight to increase pretty quickly these last few weeks. I just cannot wait to meet these baby twins!!! #twinpregnancy -50% OFF FLASH SALE NOW ON! No Code Required- Just click the link in my bio-
Guidolin isn't the only model mom who has been documenting her pregnancy through social media. Sarah Stage shocked fans earlier this year with her tiny and toned baby bump. In April, she gave birth to son James Hunter.