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Mix the milk or formula in a separate bowl or cup. When you prepare the formula in the bottle, there is an increased chance that air bubbles will form. Make sure to stir the formula slowly so that you minimize the number of air bubbles that form. Instead, get the bowl or cup as close to the lip of the bottle as possible, and slowly pour the formula into the bottle. If you pour the formula out of the cup and into the bottle from a great height, the formula will hit the bottom of the bottle and form bubbles. Pouring the formula slowly also helps to make sure that the liquid does not trap air as it gets poured into the bottle. If you must prepare the formula in the bottle, stir the formula rather than shaking the bottle. When you shake the bottle, or handle the bottle roughly, air bubbles are more likely to form. Stir the formula with a wooden stick or knife to make sure that it is mixed in well. Try to prepare the formula at least five to ten minutes before your baby’s normal feeding time. Letting the bottle sit once you have poured the formula into it will help any lingering bubbles to settle and disperse. Preparing your baby’s formula ahead of time will keep you from rushing through the preparation process. When you rush, you are more likely to stir the formula quickly, which causes bubbles to form. Talk to your pediatrician about what products you should use and how many drops you should add to the bottle. In addition to this, it is always important to read the instructions that come with the drops.  “Mylicon” drops are commonly used for this purpose.These drops contain simethicone, an ingredient that helps the breakdown of gases and air bubbles, and is not harmful for babies. “Tummy calm” is a homeopathic medicine that prevents gases with the help of natural ingredients like chamomile, thuja, and silicea. Gas drops can be expensive, and some studies suggest that they may not be very effective. However, they appear to be safe, so they shouldn't harm your baby if you do decide to try them. If you are able to fill the bottle up all the way, there will be less room for air bubbles to form.

Summary:
Prepare the formula or milk in advance. Avoid pouring the milk from high above the bottle. Avoid shaking the bottle. Allow the bottle time to stand before you give in to your baby. Consider using drops that will reduce the amount of air bubbles that form in your formula. Use bottles that can only contain enough milk for one whole feeding.