Hemorrhoids affect both men and women equally. They are often caused by straining when having a bowel movement. However, some women can experience hemorrhoids when pregnant. 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. Exercise and increased fiber in the diet can help reduce constipation and straining by producing stools that are softer and easier to pass.