According to a study in Pediatrics, there was a small reduction in the rate of sudden unexpected infant death (SUID) from 1999 to 2015, Health Day reports. However, other causes of sudden infant death, such as accidental suffocation and strangulation, increased.

Researchers found that from 1990 to 2015 there was a decrease in SUID rates from 154.6 to 92.4 per 100,000 live births, with a 44.6% decrease from 1990 to 1998 and a 7% decrease from 1999 to 2015. From 1999 to 2015 there was a 35.8% decrease in SIDS rates, a 183.8% increase in accidental suffocation and strangulation rates, and no significant change in the rates of unknown cause. Among states, there was considerable variation in SUID trends from 41.5 to 184.3 in 2000 to 2002, and from 33.2 to 202.2 in 2013 to 2015.

“Reductions in SUID rates since 1999 have been minimal, and wide variations in state-specific rates remain,” the authors write. “States with significant declines in SUID rates might have SUID risk-reduction programs that could serve as models for other states.”