Why should we stop boiling water to prepare bottles at 4 months? Can I continue doing this beyond 4 months?

It is recommended to boil water and sterilize bottles when preparing bottles for infants who are 4 months old or younger because their immune system is still developing and may not be able to effectively fight off infections. However, after 4 months, it is not as necessary to continue boiling water and sterilizing bottles as the baby's immune system is stronger. It is ultimately up to you whether you want to continue this practice, as it becomes more of a personal choice rather than a requirement.