Babies should not have blankets in their crib before they are 12 months old due to safety concerns. The American Academy of Pediatrics (AAP) and other health experts recommend keeping soft objects and loose bedding out of a baby's sleeping area for at least the first year. This is to reduce the risk of accidental suffocation and sudden infant death syndrome (SIDS), as infants under 12 months lack the motor skills to move a blanket away from their face. The safest time to introduce a blanket is generally after 12 months, when the baby has developed enough motor skills to move the blanket off their face and change positions. Some experts suggest waiting until 18 months or even 2 years old for added safety. When introducing a blanket, it should be breathable, lightweight, and tucked firmly at the bottom of the crib, coming no higher than the baby's chest to prevent it from covering the head during sleep. In the meantime, to keep a baby warm without using a blanket, parents can use swaddles (until the baby can roll over), wearable sleep sacks, footed pajamas, and ensure the room temperature is comfortable (around 68-72°F). In summary:

• No blankets in crib for babies under 12 months.
• Safe introduction typically from 12 months or later (up to 18 months or 2 years).
• Use alternatives like swaddles or sleep sacks for warmth in the first year.
• When introducing a blanket, ensure it is breathable, lightweight, and properly tucked in.

These guidelines are to ensure the baby's safety while sleeping and to minimize risks related to blankets in the crib.