Hemorrhoids are common colon problems that affect both men and women equally. They can be internal (inside the anus) or external (under the skin around the anus), and occur when the veins around the anus or lower rectum become swollen and inflamed. Roughly half of the population has hemorrhoids by age 50. They are particularly common among pregnant women because of hormonal changes and the pressure of the fetus in the abdomen. Hemorrhoids are often caused by straining during stool movement; but other factors that can lead to this condition include aging, chronic constipation or diarrhea, and anal intercourse. A few ways to prevent hemorrhoids include emptying your bowels as soon as possible after the urge occurs and keeping stools soft -- by increasing fiber in the diet and exercising -- so that they pass easily.