Then allow them to dry on a clean towel. After that, a good cleaning in hot, soapy water or a cycle through the dishwasher is sufficient. If you have well-water, repeated sterilization of the bottles may be best. Add your comments to the bottom of this page. Indeed, if your baby is accustomed to drinking bottles at room temperature or slightly cold, you save yourself the time and hassle of preheating bottles, especially when she's crying to be fed right now.
Microwave heating can also cause a breakdown of the nutrients in formula.
Like so much with babies, you'll need to listen and observe. If you hear a lot of noisy sucking sounds while she drinks, she may be taking in too much air. To help your baby swallow less air, hold her at a 45-degree angle. Also take care to tilt the bottle so that the nipple and neck are always filled with formula. Never prop a bottle.