You can generally stop sterilizing baby bottles when your baby is around 12 months old, according to guidelines from the UK's National Health Service (NHS). The NHS emphasizes the importance of sterilizing all feeding equipment, including bottles and teats, until the baby reaches at least 12 months to protect against infections such as diarrhea and vomiting. This recommendation applies if your baby is fit and well. If your baby has health issues or a weakened immune system, you might need to continue sterilizing for longer. Before 12 months, especially the first three months, sterilization is crucial due to the baby's still developing immune system. After about 3 months, for healthy babies, you can gradually reduce the frequency of sterilizing but not stop completely until around 12 months. Some experts note that once babies start putting many things in their mouths (around 4 months), sterilizing remains important to specifically prevent bacteria growth in bottles and teats, which are warm, moist environments conducive for germs. In summary:

• Sterilize all bottles and feeding equipment until at least 12 months old.
• You can reduce sterilizing frequency gradually after 3 months if baby is healthy.
• Continue longer if baby is premature, immunocompromised, or has health concerns.
• Once baby is 12 months old and healthy, sterilizing can generally stop.

Always consider consulting your pediatrician for personalized advice based on your baby's health.