Breast pumping works best when you have the right flange size, a consistent routine, and a few techniques to help your milk flow. Whether you’re pumping at work, building a freezer stash, or exclusively pumping, the process follows the same core steps: prepare your equipment, trigger your let-down reflex, pump for the right amount of time, and store your milk safely.
Getting the Right Flange Size
The flange (the funnel-shaped piece that sits over your nipple) is the single most important piece of equipment to get right. A poorly fitting flange causes pain, reduces output, and can even damage tissue. To find your size, measure the diameter of your nipple at the base, not including the areola. Then add 2 to 3 millimeters. So if your nipple measures 16mm across, you need a 19 or 20mm flange.
Measure both sides, because they’re often different. When the fit is correct, your nipple moves freely inside the tunnel without rubbing against the walls, and only a small amount of areola gets pulled in. If your nipple is pressing against the sides of the tunnel, the flange is too small. If a large portion of your areola gets sucked in and you feel discomfort or swelling, it’s too large. Your size can also change around 10 weeks postpartum once your supply stabilizes, so it’s worth remeasuring if pumping starts to feel different.
Triggering Your Let-Down
Milk doesn’t flow just because suction is applied. Your body needs to release milk through a reflex controlled by hormones in the brain, and stress, anxiety, caffeine, and nicotine can all suppress it. This is why many people sit down at a pump and get very little at first. Cranking up the suction won’t fix it. The issue is your let-down reflex, not the vacuum pressure.
Before you start pumping, take a minute to get calm. Look at a photo of your baby. Bring along a small piece of clothing that smells like them. Try slow, deep breaths or visualize your baby nursing. These small steps prime your brain to release the hormones that trigger milk flow. Once let-down happens (you’ll typically feel a tingling sensation or see milk start spraying), the pump can do its job effectively.
How Long and How Often to Pump
Match your pumping frequency to how often your baby eats. A newborn typically feeds 8 to 12 times in 24 hours, so if you’re exclusively pumping, aim for that same range. If you’re pumping while also breastfeeding (for example, at work), pump each time you miss a feeding. This signals your body to keep producing the right amount of milk.
Most sessions last 15 to 20 minutes per breast, or about 20 to 30 minutes if you’re double pumping. You’ll notice the flow slow to a trickle or stop. That’s your cue to finish. Pumping much longer than that doesn’t yield more milk and can actually reduce blood flow to the nipple, cause pain, and even break down the skin. If you’re struggling to pump enough, add an extra session to your day rather than extending individual sessions.
Using Hands-On Technique for More Milk
One of the simplest ways to increase your output is combining breast massage with pumping. Gently compressing and massaging the breast while the pump is running helps drain areas the suction alone can miss. Research from UW Health found this technique increases milk volume by up to 48% and pulls out more of the fatty hindmilk that supports your baby’s growth.
To do this, use your free hand (or both hands if you’re using a hands-free pumping bra) to gently press and knead the breast from the outside toward the nipple while pumping. You’re not squeezing hard. Think gentle, rhythmic compression. This is especially helpful in the last few minutes of a session when flow has slowed down.
Power Pumping to Build Supply
If your supply needs a boost, power pumping mimics the cluster feeding a baby does during growth spurts. Set aside one uninterrupted hour, ideally in the morning when milk production tends to be highest. Follow this pattern: pump for 20 minutes, rest for 10, pump for 10, rest for 10, pump for 10. This repeated stimulation signals your body to ramp up production. It typically takes two to three days of daily power pumping sessions before you notice an increase.
Closed vs. Open System Pumps
You’ll see pumps described as “closed system” or “open system.” A closed-system pump has a barrier (sometimes called overflow protection) between the milk and the motor, usually located between the tubing and the pump or within the shield connector. This prevents milk from backing up into the tubing or motor if a bottle overfills or you lean back while pumping. It also means the tubing rarely needs cleaning.
An open-system pump lacks that barrier, so milk can potentially reach the tubing. That said, a closed system isn’t automatically more hygienic. Bacteria and mold grow from poor cleaning regardless of pump type. The real advantage of a closed system is convenience: less tubing maintenance and the freedom to pump in a more reclined position.
Cleaning Your Pump Parts
Every part that touches milk needs to be cleaned after every session. Rinse the parts under running water first to remove residual milk, then wash with regular dish soap (not antibacterial soap, which can contain additives that aren’t safe for daily use on feeding equipment). Rinse thoroughly to remove all soap, then set everything on a clean, unused dish towel or paper towel to air dry completely. Don’t pat or rub parts dry with a towel, because that can transfer germs back onto them.
Sanitizing (using steam, boiling water, or a dishwasher’s sanitize cycle) should happen at least once a day if your baby is under two months old, was born premature, or has a weakened immune system. For older, healthy babies, daily sanitizing is optional as long as you’re cleaning thoroughly after each use. If you run parts through a dishwasher with hot water and a heated drying cycle, that counts as both cleaning and sanitizing.
Tubing doesn’t need routine cleaning when used correctly, because it shouldn’t come into contact with milk. But if you ever see milk or mold inside the tubing, throw it away and replace it. Mold inside tubing is nearly impossible to clean properly.
Storing Pumped Milk Safely
Freshly pumped milk stays safe at room temperature (77°F or cooler) for up to 4 hours. In the refrigerator, it lasts up to 4 days. In the freezer, 6 months is ideal, though up to 12 months is acceptable. Label every container with the date so you can use the oldest milk first. Store milk in the back of the fridge or freezer where the temperature is most consistent, not in the door.
Signs Something Isn’t Right
Pumping should not hurt. Pain is a signal that something needs adjusting, usually the flange size or the suction level. If your nipple is being compressed against the flange tunnel, size down. If you see significant swelling or blanching (white patches on the nipple), turn the suction lower. The goal is to use the highest comfortable suction, not the highest possible suction.
Watch for cracked or broken skin on or around the nipple, which can result from too-small flanges combined with high suction over long sessions. If you’re pumping for 20 minutes and getting very little milk despite having an established supply, the issue is more likely a let-down problem or a flange fit issue than a supply problem. Adjusting your environment, flange size, or adding breast compressions usually makes a bigger difference than pumping longer or harder.