Piles, also known as hemorrhoids, are swollen veins and muscle around your anus or in your anal canal. Your anal canal is a short, muscular tube with blood vessels that connects your rectum (back passage) with your anus. Piles can develop when this tissue becomes swollen, possibly as a result of straining on the toilet. Sometimes, piles can be painful and bleed if they become damaged.
Piles are also common during and after pregnancy. They may develop due to changes in the hormones (chemicals) in your body and the increased pressure in your abdomen (tummy), although doctors aren't sure. They usually get better once your baby is born.