I have heard so many negative comments from mothers throughout the years about these pumps that I can only recommend one - the Medela MiniElectric. Most small electric/battery type pumps do not cycle automatically. You have to put your finger on a hole or a button and release it repeatedly to create intermittent suction. Since babies nurse about once every second, ideally a pump should cycle between 40 and 65 times every minute. With these semi-automatic pumps, it is difficult to get them to cycle more than 10 times per minute. The MiniElectric cycles automatically about 32-34 times per minute, which much more closely simulates a baby's sucking pattern. Because this is still not as many cycles per minute as a baby generates, the MiniElectric is only recommended for occasional use. If you are a stay at home mom, and want to pump every now and then so you can have relief bottles, this may be the right pump for you. It is much more efficient and easier to use than hand or manual expression, and is great for travel because of it's small size and battery option. (See product information for photo and more details about the MiniElectric).
If you are going to be pumping regularly, or if time is an important consideration, you really need to be double pumping with a larger, more efficient (and more expensive) professional or hospital grade pump. In situations where you must be separated from your baby for extended periods of time, such as a premature infant, and the only stimulation your breasts will receive is from the pump, you ideally should use a hospital grade pump such as Medela's 015 Classic. This type of pump is much heavier than other pumps, and would cost about $1450.00 to purchase, so most mothers rent it. It provides the best possible stimulation for maintaining your milk supply when medically indicated.
Some insurance plans will pay the cost of rental for hospitalized infants. Call Medela's toll free number (1-800-TELLYOU) to find a rental station in your area. If you live in the Winston-Salem area, contact me as I have them available (see home page for information on the local rental options available for pumps and baby scales).
There are two other professional grade Medela pumps available for rental or purchase that provide adequate pressure and stimulation for frequent, long term use, and allow double pumping. These are the 016 Lactina Select (available for rental) and the PumpInStyle (available for purchase). All three types of pumps (015, 016, and PumpInStyle) meet the criteria for optimal suction pressure and cycling, and allow you to single or double pump and adjust the suction levels. The Lactina and the Pump In Style also allow you to adjust the cycling speed.
When a baby nurses he generates about 200-250 millimeters of negative pressure and sucks 45-60 times per minute. Pumps that provide pressure levels above the high 200s can cause pain, and levels below 150 are not effective at removing milk. The most efficient pumps create pressure levels between 200-230 millimeters and cycle about once every second or so. Medela's ManualEase, MiniElectric, PumpInStyle, 015 Classic and 016 Lactina Select all have pressure levels around 220 when set on maximum.
Double pumping is an important feature. Not only does it cut your pumping time in half (from 20-30 minutes with single pumping) to 10-15 minutes or less, but your prolaction levels are higher when you double pump, so you actually produce more milk in less time. This is especially important when you are pumping frequently, or when you are working or in school and have limited break time in which to pump.
Don't be surprised if you get more milk from one breast than the other when you double pump, because each breast functions independently of the other. Some mothers will get 3 or 4 times as much from one breast as the other, and some will notice only a subtle difference in the amount they get from each side. It would be unusual for each breast to produce exactly the same amount.
The 016 Lactina Select is portable and popular with working mothers. It costs over $700 to purchase, so most mothers rent it instead. Some mothers prefer to rent rather than purchase a pump because they want to try a professional-grade pump before purchasing one, or because they only plan to nurse for a short time.