The U.S. has the highest rate of unexpected infant death among all developed nations, and progress toward addressing this problem has slowed, according to a new study by researchers from the Centers for Disease Control and Prevention (CDC).

That's in part because unsafe practices (including parents who place infants to sleep on their stomachs instead of their backs) persist. 

An estimated 3,500 infants die during sleep each year in the U.S. Though a tiny percentage of the 4 million babies born, these sudden unexpected infant deaths (SUIDs) remain a leading cause of death among children under one. (SUID includes sudden infant death syndrome, the death of an infant without a known cause, as well as other sleep-related infant deaths such as accidental suffocation.)  

In the new study, published in the journal Pediatrics, CDC researchers analyzed death certificates and found that infant sleep deaths dropped 40 percent between 1990 and 2015. But most of this decline occurred in the 1990s, with the rate nearly plateauing between 1999 and 2015.

In some states, the rate has actually increased from 1990. In Alaska, Arkansas, Alabama, Kentucky and Louisiana, for example, the rate of unexpected infant death remains higher today than it was nationally in 1990.

Here, a look at SIDS in the U.S., and what parents can do to keep babies safe.  

Why Progress Has Stalled

Researchers are still investigating exactly why progress on curbing infant deaths has slowed.

One major contributor, however, is clear: Some unsafe sleep practices continue to be relatively common. These include having soft bedding in a crib (such as blankets), putting infants to sleep on their stomachs, and bed sharing with adults. The rate of infant bed sharing, for example, doubled between 1993 (6.5 percent) and 2010 (14 percent).

Smoking during pregnancy, another major risk factor for SIDS, has continued to become less common in the U.S., but the five states where infant deaths are highest and climbing are also among those with the highest maternal smoking rates. Eliminating all smoking during pregnancy would prevent one-third of all SIDS deaths, researchers estimate.

And although smoking rates have fallen, opioid use is increasing across the country, potentially further jeopardizing progress. While it’s too soon to assess whether the opioid epidemic has contributed to the stalled progress in reducing infant death, infants exposed to opioids have a 3 to 15 times greater risk of SIDS. 

What Makes the U.S. Different

“Parents make their infant care decisions largely on the basis of what they perceive will keep their infant both safe and comfortable,” write Rebecca Carlin, M.D., and Rachel Moon, M.D., both pediatricians who study SIDS, in an editorial that accompanied the new study in Pediatrics. “For behavior change to occur, health care and public health professionals will need to understand and address parental concerns about safety and comfort.”

For example, 1 in 4 U.S. babies is still put to sleep on the stomach because parents worry about choking or believe children will sleep longer. Less than 5 percent of babies in other developed countries sleep on their stomach.

More About Pregnancy and Babies

Some U.S. parents also use soft bedding in an effort to make babies more comfortable; others believe bed-sharing helps monitor and protect their babies.

To address these potentially dangerous misconceptions, health officials and providers need to redouble efforts to promote safe sleep practices, argue Carlin and Moon, who call for better communication with parents, more effective public health messaging, and better use of technology to reinforce safe sleep guidelines and counter misinformation online.

Another reason the U.S. lags behind other countries may be due to “fragmentation in the healthcare system,” says Lori Feldman-Winter, M.D., M.P.H., a member of the American Academy of Pediatrics Task Force on SIDS and a professor of pediatrics at Cooper Medical School of Rowan University. “It’s possible having universal coverage by a one-payer system would eliminate most of the differences seen.”

Unlike other developed countries, the U.S. also lacks mandated paid maternity leave and postpartum home visits that can help “establish a social norm for safe sleep,” Carlin and Moon write.

“Many healthy infant care practices, [such as] breastfeeding, [back] sleep position and safe infant sleep location, cease when the mother returns to work because of poor work support, new caregivers or the need for increased parental sleep,” they write. 

What Parents Can Do

While SIDS can be a scary thing to contemplate, parents are not powerless.

Parents should know and abide by these recommendations from the American Academy of Pediatrics, designed to promote safe sleep for infants: 

Place babies to sleep on their back, on a firm mattress not shared with anyone else. A baby’s risk of SIDS is 2 to 13 times greater when sleeping on the stomach, research has found.
Remove all soft or loose objects from the baby's sleeping area, including blankets, pillows, crib bumpers, and toys.
Never put babies to sleep on couches, sofas, armchairs, or similar furniture.
• Give infants a pacifier at nap time and bedtime.
• Avoid smoking during and after pregnancy.
• Share a room—but not a bed—with babies until they are at least 6 months old.
• Breastfeed as long as possible in a baby’s first year. Breastfeeding cuts SIDS risk in half, research has shown.
• Vaccinate children according to the CDC’s recommended immunization schedule