Nursing bottles usually come in three basic sizes: 4-ounce, 8-ounce, and 9-ounce. The smallest are typically used for newborns, but they can double as storage for expressed milk or, when baby gets older, as juice or water bottles. The larger bottles tend to be more versatile and long lasting.
There are enough types of bottles available today to make you wonder which one is right for your baby. However, they can be broken down into basically three categories:
Standard bottles These have straight necks and bodies and can be used over and over again. All bottles are marked in ounces for easy and precise portion control. It's best to buy clear plastic or glass bottles so that you can observe the milk flow as baby drinks it.
Bottles with angled necks Designed to keep the nipple filled with liquid to reduce baby's air intake, bottles with angled necks also promote holding baby's head in an upright position. Many doctors believe that feeding in this position helps prevent ear infections.
Disposable systems Disposable systems have a hard plastic shell called the nurser, which holds disposable plastic bags. For one-time use, the bags are pre-sterilized to hold formula. The system comes with a special nipple and screw-on collar that holds the bag in place. The advantage of this system is that the disposable bags contract to prevent babies from sucking in air bubbles that cause them to spit up. Plus, it is ready to use and requires no cleaning. The nipples, however, need to be thoroughly cleaned, as with any bottle.