How is "Metaphors" related to pregnancy?

The major clue that the speaker is a woman,
and a pregnant one, is line 7 (“I’m … a cow in calf”), but the entire poem makes this
conclusion certain. The nine syllables are the nine months of pregnancy. The pregnant
woman is a riddle because (a) even today there is much unknown about pregnancy, and (b)
traditionally, the results of pregnancy are not known until birth. The poem is a riddle
because one has to determine the identity and condition of the speaker. The imagistic
references suggest size, ripeness, increase, and wealth. They all are parts of normal
feelings of pregnancy, especially the expectant mother’s awareness that she cannot get
off the train she is on (line 9). Some of the images—the melon and tendrils, the
elephant—are funny, for however big she might feel, a pregnant woman is not elephantine.
None of the images is shocking or demeaning; indeed, the speaker’s sense of herself as
having “fine timbers” or being a “fat purse” conveys her happiness with herself. The
aspect of early pregnancy suggested by the green apple is morning sickness, while the
stage shows the speaker’s awareness that she is the means by which the human race
continues itself. The onrushing train conveys the speaker’s sense that she is being
carried along by forces beyond her control. Students may wish to apply this image to
situations in life other than pregnancy.