At 3 months old, you can transition from swaddling to using a sleep sack. Most babies outgrow the startle reflex and become more active, making swaddling less effective and potentially unsafe. A sleep sack provides a safer sleep environment, reduces the risk of suffocation, and allows your baby's arms and legs to move freely while keeping them cozy. Choose a sleep sack appropriate for the room temperature, and ensure it fits your baby well
For a 4-month-old, you can use a sleeveless or short-sleeved sleep sack with ample leg room. Look for a sleep sack made from breathable and soft materials, such as cotton or bamboo, to ensure comfort. A 1.0 TOG sleep sack is generally suitable for moderate room temperatures around 20-24°C (68-75°F). Ensure the sleep sack is the right size for your baby's weight and height to prevent any safety hazards.
No, sleep sacks do not hinder a baby's development. In fact, sleep sacks can be beneficial for a baby's safety and comfort during sleep. Sleep sacks are designed to provide a secure and cozy sleeping environment while reducing the risk of suffocation associated with loose blankets.