Warm bottles only when your baby prefers it, and use gentle, outside-in heat with strict timing for leftovers. This guide gives a practical home routine for breast milk and formula without microwaves or overheating. Learninghow to warm baby bottles effectively can make your 2:00 AM routine much smoother. Is your baby crying at 2:00 AM while you stand at the sink wondering whether the bottle is too cold or too hot?