About 40 percent of pregnancies across the United States were unwanted or mistimed, according to the first-ever state-by-state analysis of unintended pregnancies.

According to the analysis released Thursday, the highest rates were in the South, Southwest and in states with large urban populations. Highest was Mississippi with 69 per 1,000 women ages 15-44; lowest was New Hampshire, with 36 per 1,000.

"There are many, many reasons why people don't plan ahead, even when it's such a crucial decision," says Claire Brindis, director of the Bixby Center for Global Reproductive Health at the University of California-San Francisco, who was not involved in the analysis.

Brindis says difficulty in finding family planning services and lack of access to birth control contribute to the high numbers of unintended pregnancies. There is "a very strong denial factor - (people think) 'this won't happen to me,' " she says.

The analysis, based on 2006 data, the most recent available, used national and state surveys on pregnancy intentions, births, abortions and miscarriages, including data from 86,000 women who gave birth and 9,000 women who had abortions. It is published online in the journal Perspectives on Sexual and Reproductive Health.

In nearly every state, about 65 percent to 75 percent of unintended pregnancies were considered mistimed and 25 percent to 35 percent unwanted, according to analysis by the Guttmacher Institute in New York, which studies reproductive issues. More than half of pregnancies in 29 states and the District of Columbia were unintended; 38 percent to 50 percent were unintended in the remaining states.

"We know we have very high levels of unintended pregnancy in the U.S., much higher than in most places around the developed world," says Kelly Musick, a sociologist at Cornell University in Ithaca, N.Y., who was not involved in the analysis.

The state breakdown was possible because additional state data became available in 2006, says lead author Lawrence Finer. Six states and the District of Columbia had no surveys; estimates were used. Among the 34 states that had data for 2002 and 2006, rates of unintended pregnancies increased in 23 states and decreased in eight; three had little or no change.

"We do a better job of planning to buy tickets to see Lady Gaga than we do about being careful in planning for when we're going to have children, how many children and when in our lives we're going to have them," Brindis says.

Explore further Increased contraceptive supply linked to fewer unintended pregnancies

(c) 2011, USA Today.

Distributed by McClatchy-Tribune Information Services.