How Breast Pumps Function

Breast milk offers incredible benefits to a baby’s development. A mother’s milk adapts to meet her baby’s specific needs. Research reveals that breast milk helps prevent and reduce the severity of various infections and health conditions such as diabetes, obesity, and asthma [source: American Academy of Pediatrics]. The American Academy of Pediatrics advises exclusive breastfeeding for the first six months of an infant’s life and continued breastfeeding for the first year if possible. But what happens if a new mom can’t breastfeed?

Some mothers want all the health benefits of breast milk but may not be able to breastfeed full-time. A breast pump offers an option to feed a premature or multiple babies with the mother’s milk. It also helps maintain milk production if the mother is on medication that can’t be passed to the baby—by pumping and discarding the milk, she can continue producing until it’s safe to nurse. Most often, breast pumps give mothers the freedom to return to work or take some personal time without worrying about missing feedings.

Breast pumps provide mobility and convenience for parents who prefer to continue using breast milk over formula feeding. Though today they seem as common as baby monitors and Diaper Genies, electric breast pumps didn’t become widely available outside hospitals until the 1990s. Interestingly, the invention of mechanical breast pumps drew inspiration from the dairy industry, specifically a 19th-century milking machine that used a pulsating vacuum and double-chambered teats to stimulate milk production [source: Bazelon, Encyclopedia of Australian Science]. In 1927, engineer and chess master Edward Lasker patented a mechanical pump to help premature babies who were too weak to nurse. Decades later, in the 1950s, Einar Egnell and Olle Larsson collaborated to develop a more efficient and comfortable version of the breast pump [source: Bazelon].

Whether you opt for the motorized or manual pump, these devices can be a lifesaver for mothers who work or those struggling with low milk supply. They also enable fathers to participate in feeding and help prevent engorgement, the painful condition caused by overly full breasts. Additionally, breast pumps can assist in drawing out flat or inverted nipples. But why isn't every baby using a bottle for breast milk? In this discussion, we'll explore the limitations of breast pumps and guide you in selecting the right one for your needs.

Expressing Milk

Before Madonna captured attention for her interest in Kabbalah, she was encouraging the world to "Express Yourself." Perhaps that iconic song and her cone bra influenced new mothers to ‘express milk’ – a term for removing milk from the body, either manually or using a pump. To understand how women use breast pumps to express milk, let’s revisit the fundamental concepts of lactation.

Following childbirth, after the placenta is delivered, the hormone prolactin signals the mother’s body to begin milk production. This typically starts three to five days after birth, and the more milk is removed (either by the baby or a pump), the more the body will produce. Suckling triggers the release of another hormone, oxytocin, which causes muscles around the milk glands to contract, ultimately opening milk ducts and releasing milk from reserves around the nipple [source: Davis]. This process is known as the milk-ejection reflex (MER) or the "let-down."

A baby typically sucks between 50 to 90 times per minute during the start of a feeding, slowing down once the let-down reflex occurs [source: Mark]. Breast pumps replicate this pattern by cycling—alternating between creating and releasing suction. Most hospital-grade and at-home electric pumps operate at a rate of 40 to 60 cycles per minute, which is roughly one pull every second.

Breast pumps differ in design and brand, but they all operate on the same fundamental principles. A plastic or glass breastshield enables suction to be applied to the breast. The flange, a cone- or funnel-shaped part of the breastshield, fits over the nipple and areola to form a seal. This creates a vacuum around the nipple, drawing it into the tunnel while pressing the areola against the flange [source: Knorr]. With manual pumps, the mother squeezes a lever or bulb to create and release suction, mimicking the natural cycling of a baby’s nursing pattern. Battery-operated and electric pumps rely on motors connected to the flanges by plastic tubing to generate suction.

The diaphragm, found in some pumps but not all manual models, contributes to creating and releasing suction. In certain pumps, such as many hospital-grade versions, the diaphragm also acts as a barrier, preventing contamination by separating the mother from the suction source [source: Knorr]. A removable, flexible valve within the pump body ensures that proper suction is maintained.

As the pump mimics the baby's natural nursing rhythm, starting with quick pulls followed by a slower, deeper phase, milk begins to flow. Milk is then collected through storage bags or ready-to-feed bottles that can be directly attached to the pump.

Types of Breast Pumps

Now that we understand how breast pumps work to extract milk from the body into bottles and containers, let’s take a look at the various types available:

Manual pumps: As discussed earlier, these pumps rely on physical effort to create suction. The user generates suction by squeezing a lever, handle, or by pumping a piston inside a larger cylinder [source: FDA]. Some models even use foot pedals to harness lower-body strength for suction. Once let-down happens, milk is collected in containers attached to the pump. Manual pumps are small, discreet, and budget-friendly, but they are slower than other types and may cause strain since the user is responsible for all the power.

Battery-powered pumps: These pumps use a small motor connected to the breastshield by plastic tubing, typically powered by AA or C batteries. Reaching the ideal vacuum might take between 10 to 50 seconds, so these pumps generally cycle about 10 times per minute [source: Knorr]. This pace is relatively slow compared to the 50 to 90 sucks per minute typical of a baby at the start of a feeding. While these pumps can be uncomfortable due to continuous suction and may take more time, they are portable, affordable, and work anywhere. Hands-free versions, which fit inside a bra and come with an AC adapter, allow milk to flow slowly into a bag through a flexible valve stem [source: Consumer Reports].

Electric pumps: Among the three types of pumps, electric pumps are the fastest and most costly. They connect to an electrical outlet, providing sufficient power to empty the breasts efficiently and thoroughly. Women can achieve maximum efficiency by using the double-pumping method, extracting milk from both breasts simultaneously, typically at a rate of 40 to 60 cycles per minute. These pumps also offer the flexibility to adjust suction rhythms according to personal preference. A hospital-grade pump, often available for rent or in medical settings, is ideal if your baby struggles to latch or you only plan to pump for a short time, usually under three months [source: Consumer Reports]. For longer-term pumping, such as if you return to work, a personal-use automatic pump may be the better choice. These pumps reduce pumping time and come with customizable settings. Unlike hospital-grade models, personal-use pumps are lightweight, portable (typically sold with discrete backpacks or tote bags), and cannot be shared between users. Some packages even include manual pumps as well.

Open and Closed Systems

Bacteria and viruses can be passed through breast milk, which is why the FDA considers most breast pumps, except hospital-grade ones, to be single-user devices [source: FDA]. Hygienic rental pumps and some newer personal-use models are designed with specific barriers and filters to prevent milk from contaminating the motor or tubing, which could otherwise lead to cross-contamination and mold development. Women who use or rent hospital-grade pumps are required to purchase a new accessory kit, including tubing, breastshields, and containers that come into contact with the milk. This setup is referred to as a closed system.

Open systems lack a barrier, meaning milk can come into contact with the motor or tubing. Depending on the design, milk can sometimes overflow into the tubing, potentially compromising the diaphragm. If the diaphragm is not removable or cannot be sanitized, sharing or reusing an open-system pump increases the risk of mixing milk from different women every time the motor is activated [source: Morbacher]. All pumps, regardless of system type, should be disassembled and cleaned thoroughly according to the manufacturer's instructions before every use.

Breast pumping, like many aspects of parenting, has its critics. Some argue that breastfeeding holds an advantage over pumping, as it fosters a closer emotional bond between mother and child [source: Lepore]. There’s also the concern that pumping could lead to nipple or breast damage if the flange doesn’t fit properly, causing friction as the nipple is drawn into the tunnel.

Choosing the Right Breast Pump

Before you decide to spend $50 on a manual pump or commit to a monthly rental, it’s crucial to choose the breast pump that best suits your needs. For some moms with limited budgets, purchasing a pump may not be an option due to its cost. Nevertheless, the Women, Infants and Children program (WIC) provides financial assistance for purchasing breast pumps and related supplies to eligible women through its Special Supplemental Nutrition Program [source: FDA].

Mothers who depend on breast pumps, but are not directly breastfeeding, should expect to pump about eight to ten times per day. Once a mother is able to produce a full milk supply, ranging from 25 to 35 ounces (739 to 1,035 milliliters) daily, she can reduce pumping to five to seven sessions a day [source: Mohrbacher]. Standard pumping sessions last approximately 10 to 15 minutes per breast.

A simple way to determine how many times you'll need to pump while at work is to divide the hours you'll be away from your baby by three [source: Mohrbacher]. If you plan on returning to work and need to store multiple containers of milk, an electric or battery-operated pump should meet your needs. Automatic pumps designed for personal use can speed up the process when you double-pump, reducing pumping time by half. Be sure to find a private space with an electrical outlet; ask your employer about the availability of a lactation room, empty office, or break room. While fresh breast milk can remain safe at room temperature (66 to 72 degrees Fahrenheit, 19 to 22 degrees Celsius) for six to 10 hours, having access to a refrigerator may offer added peace of mind [source: Mohrbacher]. Many experts recommend varying storage methods and temperatures, so check with your doctor for advice on how long to freeze or refrigerate milk.

If you're combining breastfeeding with pumping and only need to express milk occasionally, a manual pump could be an economical option. The same guidelines for handling and storing milk apply to manually expressed milk -- be sure to label storage containers with the date and time to prevent spoilage.

Breast Pumping Tips

Even after selecting the right pump, it will take some time to become familiar with your body and perfect the pumping process. Try these tips to help make the experience a bit easier:

Breast pump manufacturers such as Medela and Ameda provide helpful tips on their websites regarding product use. A valuable resource for moms is La Leche League, a global organization dedicated to educating families, lawmakers, and communities about breastfeeding. If you prefer personalized advice, contact your local hospital to inquire about lactation consultants. These experts can answer any questions you may have about breastfeeding and pumping and offer guidance on how to keep your baby thriving.