Using a breast pump comes down to four things: getting the right flange fit, finding a comfortable suction level, pumping often enough to build or maintain your supply, and keeping everything clean. Each of these is straightforward once you know the basics, but getting any one of them wrong can lead to pain, low output, or both. Here’s how to get it right from the start.
Get the Right Flange Size First
The flange (also called a breast shield) is the funnel-shaped piece that sits over your nipple. If it doesn’t fit correctly, pumping will hurt and you’ll get less milk. Many people use the flange that came in the box without checking the size, which is one of the most common reasons pumping feels uncomfortable.
To find your size, measure the diameter of your nipple at the base using a ruler or measuring tape. Measure in millimeters and don’t include the areola, just the nipple itself. Then add 4 mm to that number. So if your nipple measures 16 mm across, you’d want a 21 mm flange.
When the fit is correct, your nipple sits centered in the tunnel and moves freely in and out without rubbing the sides. Two signs that something is off:
- Too small: Your nipple rubs along the sides of the tunnel, causing friction and soreness.
- Too large: Your nipple plus a large amount of areola tissue gets pulled into the tunnel, which can cause pain and reduce suction efficiency.
One thing that catches people off guard: nipples often expand during a pumping session. A flange that looks like a perfect fit in the first few minutes may actually be too small by the end. Check the fit throughout the session, not just at the start.
How to Set Up and Start Pumping
Before your first session, wash all parts that will touch your skin or milk with soap and water. Assemble the pump according to its instructions, making sure valves and membranes are seated correctly. A loose valve is the most common reason for weak suction.
Center the flange over your nipple so it’s not angled to one side. Turn the pump on at its lowest setting and gradually increase the suction until you feel a firm, rhythmic pull that isn’t painful. Many pumps have a “letdown” or stimulation mode that uses faster, lighter cycles to trigger your milk to start flowing, then switches to a slower, deeper cycle for expression. If your pump has this feature, start there and switch to the expression mode once you see milk flowing steadily.
A common mistake is cranking the suction as high as you can tolerate, thinking it will produce more milk. It does the opposite. Pain triggers stress hormones that actually inhibit the milk ejection reflex, and high suction can compress the milk ducts in a way that slows flow. Set the suction at the highest level that’s still genuinely comfortable. If it hurts at all, dial it back.
How Often and How Long to Pump
How frequently you need to pump depends on your baby’s age and whether you’re pumping exclusively or supplementing breastfeeding.
With a newborn, plan on 8 to 10 sessions in a 24-hour period, which mirrors how often a newborn typically eats. That works out to roughly every 2 to 3 hours, including at least once overnight. By around 3 months, most people can drop to 5 or 6 sessions per day as each session yields more milk. By 6 months, 4 sessions a day is often enough to maintain supply.
Each session typically lasts 15 to 20 minutes, or about 2 to 5 minutes after the last drops of milk stop flowing. Pumping well past the point of empty milk flow doesn’t meaningfully increase output and can cause unnecessary soreness.
Hands-On Techniques for More Milk
If you want to get more milk per session, try breast compressions while pumping. While the pump is running, use your free hand to gently squeeze the breast and hold the pressure. Don’t roll your fingers toward the nipple, just compress and hold. You should see milk flow increase or restart. Release when the flow slows, then compress again in a different spot.
Applying a warm compress or gently massaging the breast before pumping can also help trigger letdown faster. Some people find that looking at a photo or video of their baby, or even just smelling something the baby has worn, helps the process along. This isn’t just anecdotal: relaxation genuinely affects the hormonal signals that release milk.
Power Pumping for Low Supply
If your supply has dipped, power pumping mimics the cluster feeding pattern babies use to signal the body to produce more milk. It’s a single 60-minute session with this pattern: pump for 20 minutes, rest 10 minutes, pump 10 minutes, rest 10 minutes, pump 10 minutes. Replace one of your regular daily sessions with a power pumping session. Most people see results within 2 to 3 days, though it can take up to a week.
Storing Milk Safely
The CDC’s storage guidelines for freshly expressed milk are easy to remember with the “rule of fours”: up to 4 hours at room temperature (77°F or cooler), and up to 4 days in the refrigerator. For longer storage, milk keeps best in the freezer for about 6 months, though it remains safe for up to 12 months.
Store milk in small portions (2 to 4 ounces) to avoid waste, since you can’t re-refrigerate milk once a baby has started drinking from it. Label each container with the date so you can use the oldest milk first. When freezing, leave a little room at the top of the bag or container because milk expands as it freezes.
Cleaning Your Pump Parts
After every session, take the pump kit apart completely and separate every piece that touched your breast or milk: flanges, valves, membranes, connectors, and collection bottles. Rinse them under running water first to remove residual milk, then wash with soap and water as soon as possible.
Beyond regular washing, sanitize all parts at least once a day. This is especially important if your baby is under 2 months old, was born prematurely, or has a weakened immune system. For older, healthy babies, daily sanitizing is less critical as long as you’re washing thoroughly after each use. You can sanitize by boiling parts in water, using a microwave steam bag designed for this purpose, or running them through a dishwasher’s sanitize cycle if the parts are dishwasher-safe.
One important note: never submerge the tubing in water or get moisture inside it. Tubing connects to the motor and isn’t meant to contact milk. If you see condensation in the tubing, run the pump with just the tubing attached (no flanges) for a few minutes to air-dry it.
When to Replace Pump Parts
Worn-out valves and membranes are a hidden cause of gradually declining output. These small silicone or rubber pieces are what create the seal that makes suction possible, and they wear out faster than most people realize.
If you’re pumping 8 or more times a day, replace duckbill valves every 2 to 4 weeks and valve membranes every 2 to 4 weeks as well. If you’re pumping 3 to 5 times daily, valves last about 4 to 8 weeks and membranes 3 to 6 weeks. Occasional pumpers (once or twice a day) can go 2 to 3 months on valves and about 2 months on membranes.
Backflow protector diaphragms, which prevent milk from reaching the motor, need replacing every 1 to 3 months depending on how often you pump. Replace any part immediately if you see tears, warping, or if a diaphragm doesn’t lie completely flat. If you notice suction feels weaker than it used to and you haven’t changed your settings, a worn valve is almost always the culprit. Keeping a spare set of valves and membranes on hand saves a lot of frustration.