When parents choose to bottle-feed their infants either pumped breast milk or formula, they need to know how to select and prepare the bottles. There is a wide range of baby bottles and nipples on the market. Most bottles today are plastic, making them virtually unbreakable. Some bottles are angled or have special vents in the bottom to prevent babies from taking in too much air with their milk, to reduce discomfort with taking in air. Other bottles use plastic liners that decompress while babies drink, to reduce air intake. Bottles come in two sizes, 4-ounce and 8-ounce. In the first month or two, parents may want to use primarily the 4-ounce bottles because babies will rarely take more than that in a sitting; later, parents may want to switch to using the larger 8-ounce bottles.
As well, parents and caregivers can experiment with the types of nipples available and determine which style is best for their baby. It is important to remember that any nipple can come with different sized holes. Smaller holes allow milk to move more slowly out of the bottle. This is better for the youngest of infants when they are learning how to eat and how to regulate their intake. If a hole is too big in the first months and allows in too much milk, the baby can choke. Larger holes allow milk to move more quickly out of the bottle. This is best for older babies, who typically like to eat faster. If a hole is too small, it can cause frustration and gas as the baby has to exert more effort to get the milk they want.
When preparing bottles, make sure that all equipment is sanitary: bottles, nipples, formula scoops, and hands. If possible, it's best that bottles and nipples are cleaned in the dishwasher on high heat between feedings. Next, for breastfeeding mothers who pump, fill the bottles and store as directed. For formula-feeding parents, follow the directions on the package exactly to prepare safe, easily digestible, nutritious meals for baby. Bottles can be heated by either mixing hot water with the formula or putting a prepared bottle in a mug of hot water to heat it from the inside out. It's not recommended to put bottles in the microwave to heat them. Microwaves can heat milk or formula unevenly, and these pockets of hot liquid can burn the baby. Milk only needs to be slightly warm to please babies; test milk temperature by splashing a little bit on the inner wrist. If the milk is too warm, allow it to cool before feeding.
Several bottles can be prepared at one time and refrigerated for up to 48 hours before feeding. If the baby does not finish a bottle, put it back into the refrigerator within 30 minutes and use it for the next feeding. Any bottle left out for longer than 30 minutes should be thrown away to prevent dangerous bacteria from breeding and fed to the baby. For the same reason, caregivers should not mix fresh formula with a partial bottle already in the refrigerator.