JACKSON, Miss. — Mississippi has the nation's highest infant mortality rate, and experts are trying to change that by teaching people about healthy pregnancies and proper sleep conditions for babies.

It's important for infants to sleep on their backs in cribs without blankets, pillows or stuffed animals, which can cause accidental suffocation, said Dr. Yvonne Maddox, deputy director of the Eunice Kennedy Shriver National Institute of Child Health and Human Development at the National Institutes of Health.

Maddox spoke Wednesday to more than 300 health care providers, social workers and others at a Jackson conference that focused on improving babies' health and reducing the infant mortality rate. The sudden infant death syndrome rate has been reduced by 50 percent since health officials started the "back to sleep" public information campaign 14 years ago, Maddox said.

"Many children are born every hour," she said. "So we need to keep the message going."

In 2011, Mississippi had 9.4 deaths per 1,000 live births. The national rate was 6 deaths per 1,000 live births. The statistics are for children who die before reaching their first birthday.

"A lot of that is because we have high poverty levels, and infant mortality goes along with poverty," said Dr. Mary Currier, Mississippi's state health officer.

The state Department of Health says the top causes of infant mortality are premature birth or low birth weight, SIDS, birth defects, accidents or maternal difficulties.

Dr. Michael C. Lu is associate administrator for the maternal and child health bureau for the Health Resources and Services Administration, part of the U.S. Department of Health and Human Services. He said children can't get a fair chance to succeed if they don't get a healthy start on life. He also pointed out that the U.S. has higher infant mortality rates for some racial and ethnic groups, such as African-Americans and Native Americans, and in some geographic regions, such as the Southeast.

"Infant mortality is a measure of how much we fail the greatness of this nation," Lu said.

Dina Ray, Mississippi, director of the March of Dimes, said her organization tries to educate women and teenagers about the importance of healthy pregnancy for infant development. That includes taking vitamins and folic acid and refraining from smoking and drinking alcohol.

She said 20 percent of babies born to teenage mothers arrive prematurely, and 14 of every 1,000 babies born to teenage mothers die before turning 1.

"One of the key problems with teen moms is that they don't actually tell anybody they're pregnant, many times, until they've been pregnant for about six months," Ray said. "By that time, they've missed out on the best part of prenatal care."

She said the lack of proper health care during pregnancy can become expensive.

"A lot of people will not get any prenatal care and then they will end up taking an ambulance three hours away, all the way into Jackson, to have a crisis taken care of," Ray said.

Cathy Files, executive director of the Mississippi SIDS Alliance, said many poor families in Mississippi can't afford cribs, so babies end up sleeping with siblings, parents or grandparents. She said she tells parents and grandparents that an infant is safest in a crib with a firm mattress and a fitted sheet. When it's cold, the infant can be put in warm pajamas. She said it can be difficult to persuade some grandparents.

"They'll be like, 'I raised 10 kids. They're all fine. And so I'm not going to change my ways,'" Files said. "But they don't understand that this is all based on research and that you never know which babies are going to be more susceptible."