You can warm up breast milk by placing it in a bowl or cup of hot water, or using a bottle warmer. Always shake or stir the breast milk to make sure that it is heated evenly.
For frozen breast milk, make sure that it is fully defrosted before heating. Defrost frozen breast milk by putting it in a bowl or cup of hot water.
Always check the temperature of the milk before feeding.
Avoid microwaving, as microwaving destroys nutrients in the milk and heats it unevenly which can burn your child. Also avoid using metal spoons or other metal objects to stir milk in glass bottles to prevent breaking them due to heat shock.