Constipation often is the result of diet or lifestyle as much as anything else. For example, people who do not drink enough fluids or eat enough fruits, vegetables, and whole-grain foods may become constipated from time to time. Also, regularity is very much a matter of habit. If you ignore the urge to have a bowel movement, or if you are frequently too busy to take the time for it, you will disrupt the normal functioning of the bowel. Stools will build up and tend to get drier and harder, making them more difficult to pass.
Constipation then becomes more likely.
Frequent use of laxatives can bring on constipation. Laxatives may clear out the bowel too completely and lead to bowel inactivity. That prompts the taking of another dose of laxative, which again overempties the bowel and often starts a cycle of frequent laxative use. This is especially true of people who are overly concerned about having regular bowel movements. Constipation is a common problem among pregnant women.