Piles during pregnancy are common due to increased pressure on the rectal veins from the growing uterus, hormonal changes causing vein relaxation, and constipation. Progesterone slows digestion, leading to straining during bowel movements, while the expanding uterus compresses blood vessels, hindering circulation. Additionally, increased blood volume and weight gain during pregnancy contribute to vein swelling. These factors collectively make pregnant women more prone to developing hemorrhoids, especially in the later trimesters.