A thorough examination will usually identify an underlying cause when a baby cries excessively for no apparent reason, and the problem is likely to be serious in only about 1 in 20 cases, a Canadian study suggests.

“Infants communicate and express discomfort by crying,” Dr. Stephen B. Freedman and colleagues from the University of Toronto, Ontario, write in the medical journal Pediatrics. “This can be due to a variety of reasons ranging from hunger or a desire for attention to severe life-threatening illness,” they note. However, “The frequency of severe underlying disease is unclear.”

To look into this question, the researchers identified 238 babies younger than 12 months of age who were brought to the University’s medical center over a 9-month period because of crying, irritability, screaming, colic, or fussiness.

Twelve children (5 percent) had serious underlying problems. Ten of these cases were correctly diagnosed at the initial visit, and the other two were diagnosed within the next week.

The most common serious diagnosis was urinary tract infection, with infants less than 1 month old having the highest rates of infection.

Source: Pediatrics, March 2009.