In some works of art, pregnancy is a symbol of wealth, fortune, fertility and/or life. Since the prehistoric ages, there are pictures or sculptures representing a pregnant woman or a woman with curves and a round belly.

I've found that example : an advertisment for a bottle of absinth from the years 1900-1910. The girl has a beautiful belly bump :3

Do you know some others work of art representing pregnant women?

   

I really don't think that painting involves pregnancy. Back in the old days, men liked women with a little bit more padding than what is fashionable now, and artists obliged, giving them wide hips a bit of padding on the belly. Gustav Klimt, however, didn't leave any ambiguity.