The pregnant supermodel - whose raises three children with husband Seal, and is expecting a daughter in October - always piles on the pounds in the last month of pregnancy, but is not worried about shifting her baby weight.
She said: "The last month is unbelievable, how rapidly your stomach goes. It's huge! The thighs, the butt - everything explodes in the end."
"It's bizarre. Just as it's a miracle that you can grow a human being in your belly, it's a miracle that your body goes back to normal again. I don't think you ever get back to exactly the way you were, but you do get close. And I'm happy with that - especially when you see your kid for the first time."
Heidi is famous for springing back into shape quickly after giving birth - she wore a bikini for a Victoria's Secret fashion show just two months after welcoming three-year-old Henry into the world.
The 36-year-old model has also spoken about her love for her 6ft 3ins tall musician husband, explaining her family is the most important thing to her.
She told Page Six magazine: "What do I love about him? Aside from his sexy stature? He's a gentle giant. We're very into family values. If you come to our house in Los Angeles you'll see that it's not a big, museum-like house where you can't touch anything or sit anywhere. It's a family house, where three children are living. We have toys all over the place."