I'm a riddle in nine syllables,
An elephant, a ponderous house,
A melon strolling on two tendrils.
O red fruit, ivory, fine timbers!
This loaf's big with its yeasty rising.
The speaker continues gently poking fun at herself, this time alluding to her body size and awkward movement. Of course a pregnant woman is also metaphorically a house for a growing fetus. 
 One could also see this as a literary allusion, for example, to the Ernest Hemingway short story “Hills like White Elephants,” though in that case the use of the word elephant probably has much more to do with expressions such as “white elephant” and “elephant in the room,” rather than the more straightforward usage in the poem.
Metaphors