In the mid-2000's, I had all my children in a row. The rules on sleeping were clear. Nothing in the crib other than a baby, wrapped like a burrito in her blanket, or in a sleep positioner if she had GERD. Other than side bumpers, nothing else was needed and should be considered dangerous. Pacifiers were an option, usually for colicky children.
Now even that has changed. Side bumpers are out. Pacifiers are most definitely in. We used crib bumpers (as almost everyone still does) in case our babies bumped against the side of the crib and hurt themselves (we always cut the strings off so they wouldn't be choking hazards).
However, according to a report on Health.com, they really don't serve that purpose at all -- especially with young infants who can't even move unless assisted. They are more decorative accents than safety measures and could cause more harm than good.
In a report from Health.com, The American Academy of Pediatrics (AAP) issued these new guidelines recently, in an effort to stem the biggest cause of death in children under the age of 1 year according to the U.S. Centers for Disease Control and Prevention -- Sudden Infant Death Syndrome (SIDS).
According to the report, the AAP discourages anything other than the baby, wrapped in a blanket, in the crib. No soft toys, no pillows, stabilizers or bumpers -- just a warm and comfortable baby. While young babies don't need any amusement or stimulation, mobiles secured to the ceiling above the crib can provide entertainment to those a bit older.
Pacifiers are also recommended for babies at bedtime although many parents don't like them as weaning the child off them when older can be really difficult. However, pacifiers have shown to also decrease the risk of SIDS, as has breastfeeding and maintaining a non-smoking home.
From EmpowHER's SIDS page, other risk factors for Sudden Infant Death Syndrome include:
Infant's age: less than 6 months old
Low birth weight
Fetal growth retardation
History of SIDS death in a sibling
History of an acute life-threatening event