The width of her heel and the width of her lower legs in skinny jeans in comparison to the wedge of the shoe she is wearing. She has a lot of fluid collecting around her ankles and the bottom part of her lower legs.  She has probably been standing for a long time and should have been wearing compression socks. I found a YouTube link for someone with pregnancy cankles that kind of demonstrates the way the fluid collects in that area.  The woman in the video is fit, pregnant and was on her feet all day for a modeling shoot. https://youtu.be/iofo7S-NuiI  She starts the little bit where she shows her ankles right around 11:34.