How are hospital populations changing? A new report reveals some surprising facts. For instance, nearly a quarter of all hospital stays are related to pregnancy and childbirth. Hospitalizations for stroke have fallen 12% from 1997 to 2002. And about 43% of all hospital admissions originate in emergency departments.

These statistics come from "Hospitalization in the United States, 2002," a report issued by the Agency for Healthcare Research and Quality. The agency published a similar report in 1997. Here are a few highlights from the new report:

* The average length of stay is 5 days.

* Women account for nearly 60% of all hospital stays. In the 18 to 44 age-group, nearly three times as many women as men are hospitalized-mainly due to pregnancy and childbirth.

* People age 65 and older, who make up 12% of the population, account for 35% of all hospital stays.

* Diseases of the circulatory system are the most common reason for hospitalization, accounting for 17% of all hospital stays.

* Depression is one of the top 10 conditions requiring hospitalization for three age-groups: 1 to 17, 18 to 44, and 45 to 64.

* The average charge per hospital stay in 2002 was $17,300-a 24% increase from 1997, when the average charge was $13,900.

The report is available at the agency's Web site, http://www.ahrq.gov/data.