Do i need to sterilize newborns bottles for at least 3months? im afraid of baby bottles shed microplastics when heated. is it still safe if i just wash the bottles with warm soapy water without boiling to sterilize?

Before first use boil the bottle and nipple in water for 5 minutes.After that you do not need to sterlize.Just wash with soap and warm water after use.You are doing the right thing washing in warm soapy water.

In cities with approved water supplies, sterilizing is overkill. A good bottle brush to get it clean and normal soapy water like you use for your own dishes is adequate. I see no reason to boil anything unless you live where you are not sure of the water source.