How Breast Pumps Work

Before Madonna made headlines for practicing Kabbalah, she was telling the world to "Express Yourself." Perhaps her song (and that infamous cone bra) served as inspiration for some new moms to express milk -- a term describing the removal of milk from the body, either manually or mechanically. To understand how women use breast pumps to express milk, let's review the basics of lactation.

After the placenta is discharged from the mother's womb as part of the birthing process, the hormone prolactin tells the mother's body to start producing milk. Her milk supply usually comes in three to five days after delivery, and the more milk that's removed (by child or pump), the more milk that comes in. Suckling triggers the body to produce another hormone, oxytocin, which contracts muscles near the milk glands and eventually causes milk ducts to widen, releasing milk from reserves located around the nipple [source: Davis]. This is known as the milk-ejection reflex (MER) or "let-down."

A baby sucks about 50 to 90 times per minute at the beginning of a feeding, slowing his or her pace once let-down occurs [source: Mark]. Breast pumps mimic this rhythm by cycling, the combination of creating and releasing suction. Most hospital-grade and at-home electric pumps follow a rate of 40 to 60 cycles per minute -- about one pull per second.

Breast pumps vary based on mechanics and manufacturers, but they all work on the same basic principles. A plastic or glass breastshield allows a vacuum to be applied to the breast. The cone- or funnel-shaped part of the breastshield, called the flange, sits over the nipple and areola to create a seal. With the creation of a vacuum around the nipple, air is pulled into the breastshield. The nipple is then drawn into the tunnel, and the areola is pressed against the flange [source: Knorr]. With a manual pump, the mother squeezes a lever or bulb to create and release suction -- a cycling effect that triggers let-down. Battery-powered and electric pumps use motors, which connect to the flanges with plastic tubing to create pull.

The diaphragm, which isn't part of some manual pumps, helps create suction and release. In some pumps, like many of the hospital-grade ones, the diaphragm also creates a barrier separating mother from suction source, preventing contamination [source: Knorr]. A detachable, membranous valve joins with the pump body to help maintain proper suction.

As the pump imitates a baby's nursing rhythm (initial rapid pulls followed by a slower, deeper phase), milk eventually flows. Storage bags and ready-to-feed bottles directly attach to the pump to collect milk.

Now that we understand how breast pumps draw milk out of the body and into bottles and containers, let's examine the different available types:

Manual pumps: As mentioned in the previous section, these devices run on old-fashioned elbow grease. The user creates suction by squeezing a lever or handle or pumping a cylinder-shaped tube within a larger cylinder (a piston) [source: FDA]. There are also foot-pedal pumps that rely on lower-body strength to create suction. Once let-down occurs, milk collects in attached containers. Manual pumps are small, discrete and relatively inexpensive; however, they work slower than other pumps and can cause strain because the user provides all the power.

Battery-powered pumps: This option relies on a small motor -- connected to the breastshield by plastic tubing -- usually powered by AA or C batteries. Because it can take 10 to 50 seconds to reach optimum vacuum, these pumps might cycle about 10 times per minute [source: Knorr]. That's not too fast if you remember that babies' nurse about 50 to 90 times per minute at the beginning of a feeding. These pumps can be uncomfortable (because of the constant vacuum) and take more time, but they're portable, affordable and work anywhere. With a hands-free pump, which fits inside a bra and comes with an AC adapter, the milk slowly travels from a flexible valve stem into a bag [source: Consumer Reports].

Electric pumps: Out of the three types, electric pumps are the most efficient and the most expensive. A cord connects the motor to an electrical outlet, allowing enough power to drain breasts quickly and completely. Women can achieve total efficacy by double pumping both breasts at the same time, usually at a rate of about 40 to 60 cycles per minute. Users are also able to customize suction rhythm by adjusting the settings. A powerful hospital-grade pump, available for rent and for users in medical facilities, is a good option if your baby has a hard time latching on or you don't plan on pumping for more than three months [source: Consumer Reports]. If you plan on expressing your milk longer than that or will be returning to work, consider personal-use automatic pumps. Like their hospital-grade counterparts, personal-use pumps reduce pumping time and feature individualized settings. As the name implies, these lightweight pumps, which usually come in discrete backpacks and tote bags, and can't be shared as hospital pumps can. Some of these pumps come packaged with manual pumps as well.

Bacteria and viruses can be transmitted through breast milk, which is why the FDA views breast pumps, except for the hospital-grade variety, as one-woman devices [source: FDA]. Hygienic rental pumps and some newer personal-use pumps are designed differently and have special barriers and filters to prevent milk from entering the motor and tubing, which could lead to cross-contamination and mold growth. Every woman who uses or rents a hospital-grade pump is required to buy a new accessory kit -- which includes the tubing, breastshields and containers that may come into contact with her milk. This is considered a closed system.

Open systems have no barrier, allowing milk to come into contact with the motor or tubing. Depending on the make and model, milk can sometimes overflow into tubing and the diaphragm may become compromised. Because some of these diaphragms cannot be removed or sanitized, if a mother shares or reuses an open-system pump, she runs the risk of exposing her milk to another woman's milk every time she turns the motor on [source: Morbacher]. Before each use, all pumps must be properly disassembled and cleaned according to manufacturer instructions.

Like many issues regarding parenting, breast pumping has its critics. Some people believe breastfeeding has an advantage over pumping because it creates an emotional bond between mother and the nursing child [source: Lepore]. Also, there is the potential that pumping may cause nipple or breast damage if a woman fails to use a proper-fitting flange (allowing the nipple to be pulled into the tunnel without any friction).

Before you decide to drop $50 for a manual pump or pay by the month for a rental, you need to figure out which breast pump makes the most sense for your lifestyle. Some moms with fixed incomes might not even consider buying a pump because of the associated costs. However, the Women, Infants and Children program (WIC) offers financial assistance for breast pumps and other related items to qualified women through its Special Supplemental Nutrition Program [source: FDA].

Moms who rely on breast pumps and aren't breastfeeding should plan on pumping eight to 10 times a day. Once a woman is able to pump a full milk supply, 25 to 35 ounces (739 to 1,035 milliliters) per day, she can decrease pumping to about five to seven daily sessions [source: Mohrbacher]. Typical pumping sessions last 10 to 15 minutes per breast.

An easy way of figuring out how many times you'll need to pump at work is to divide the number of hours you're not with your baby by three [source: Mohrbacher]. If you plan on returning to work and will be storing several containers of milk, an electric or battery-powered pump should satisfy your needs. Personal-use, automatic pumps can extract milk faster when you double-pump -- cutting pumping time in half when both breasts are emptied at once. You'll want a private spot with an electrical outlet, so ask your employer about a lactation room, empty office or break room. Though fresh breast milk stays good for six to 10 hours at room temperature (66 to 72 degrees Fahrenheit, 19 to 22 degrees Celsius), you might feel more confident with access to a refrigerator [source: Mohrbacher]. Many experts advocate different storage guidelines and temperatures, so ask your doctor how long he or she recommends freezing or refrigerating milk.

If you're pumping in addition to breastfeeding and only need to express occasionally, manual pumps could be an affordable answer. The same handling and storage rules apply to manually expressed milk -- make sure to label containers with the date and time to avoid spoilage.

Once you have the right pump, it will still take a while for you to learn to read your body and master the process. Following these tips might make expression go a little smoother:

Breast-pump manufacturers like Medela and Ameda feature helpful hints on their Web sites about their products and the best ways to use them. Another helpful resource for moms is La Leche League, an international organization that educates and informs mothers, legislative members and the community about breastfeeding. If you prefer to talk with someone one on one, contact your local hospital and find out if they employ lactation consultants. These staff members can answer any questions you may have in regards to breastfeeding and pumping, and can show you the best ways of keeping your baby happy and healthy.