Yes, you can pump one breast while your baby nurses on the other, and it’s one of the most efficient ways to collect extra milk. The let-down reflex triggered by your baby’s suckling affects both breasts simultaneously, so attaching a pump to the opposite side captures milk that would otherwise leak into a nursing pad. This approach saves time, increases total output, and produces milk with a higher fat content compared to pumping each breast separately.
Why It Works So Well
When your baby latches and begins nursing, your brain releases hormones that trigger milk ejection in both breasts at once. That’s why many women notice leaking from the non-nursing side. Pumping during this natural let-down takes advantage of a reflex that’s already happening, meaning you don’t need to create it artificially with the pump alone.
Research published in Breastfeeding Medicine found that expressing both breasts simultaneously (rather than one at a time) produces milk with significantly higher fat content. The overall cream content of simultaneously expressed milk measured 8.3% compared to 7.3% when breasts were expressed one after the other. The difference was even more striking in the last drops of milk: 12.6% cream content during simultaneous expression versus 10.5% sequentially. Higher fat content signals better breast drainage, which also helps maintain your supply over time.
Three Ways to Collect From the Other Side
Silicone Suction Collectors
These are the simplest option. A silicone collector (like the popular Haakaa-style devices) attaches to your non-nursing breast with gentle suction created by squeezing the base. It draws out more than just leaked milk, actively pulling from the breast using light, passive pressure. No cords, no batteries, no noise. Most women collect between one and three ounces per session this way.
One thing to be aware of: because these collectors create real suction, using one at every single feeding can sometimes lead to oversupply. If you notice recurring plugged ducts, engorgement between feedings, or your baby struggling with a fast flow, scale back to using it only once or twice a day.
Milk Collection Cups
Even simpler than silicone collectors, these cups sit inside your bra with no suction at all. They just catch whatever leaks naturally during let-down. You won’t collect as much milk this way, but there’s virtually no risk of stimulating oversupply. They’re a good fit if you want to save leaked milk without actively expressing.
Electric or Manual Breast Pump
Using an actual pump on one side while nursing on the other gives you the most control over suction strength and yields the most milk. A hands-free pumping bra is essential here, since you’ll need both arms: one to hold the pump flange in place (or let the bra do it) and one to support your baby. Electric pumps are more efficient and free up your hands, but they’re also louder and involve more setup. A manual pump is quieter and more portable but requires you to squeeze the handle repeatedly, which can be tricky while holding a baby.
Positioning Tips
The football hold tends to work best for simultaneous pumping and nursing. In this position, your baby lies along your forearm on one side with their feet pointing toward your elbow and ribs, and their head at your breast. This keeps the opposite breast completely clear for a pump flange or collector. A firm nursing pillow helps enormously because it supports your baby’s weight, freeing your hands.
The cradle hold also works, though it can crowd the other breast depending on your body and your baby’s size. If you’re using a silicone collector, the cradle hold is usually fine since the collector is small and lightweight. With a full pump setup, the football hold or a laid-back reclined position tends to be more practical.
Whatever position you choose, get your baby latched and settled first. Once they’re nursing comfortably, attach the pump or collector to the other side. Trying to do both simultaneously from the start often leads to a frustrated baby and spilled milk.
How Much Extra Milk to Expect
Most women collect between one and four ounces from the pumped side during a nursing session, though this varies widely based on time of day, how full the breast is, and how strong your let-down reflex tends to be. Morning sessions typically yield more because prolactin levels are highest overnight. Don’t be discouraged by small amounts at first. Even half an ounce per session adds up to several ounces a day, and over a week that’s enough for multiple stored bottles.
Storing the Milk You Collect
Freshly expressed milk stays safe at room temperature (77°F or cooler) for up to four hours. In the refrigerator, it lasts up to four days. If you won’t use it within four days, freeze it right away. Frozen breast milk is best used within six months, though it remains acceptable up to 12 months.
Store milk in food-grade glass or plastic containers with tight lids, or in bags designed specifically for breast milk storage. Freeze in small amounts of two to four ounces to avoid waste. Leave about an inch of space at the top since milk expands when frozen. Label every container with the date, and place it toward the back of the fridge or freezer rather than in the door, where temperature fluctuates.
When you’re ready to use frozen milk, thaw the oldest batch first. You can thaw it overnight in the refrigerator, under lukewarm running water, or in a container of warm water. Never microwave breast milk, as it creates hot spots that can burn your baby’s mouth and degrade nutrients. Once thawed, use refrigerated milk within 24 hours. Once warmed to room temperature, use it within two hours.
Common Concerns
Some parents worry that pumping while nursing will “take milk away” from the baby. In practice, the opposite tends to be true. Your baby always has priority access to the breast they’re on, and the pump on the other side is collecting milk that would otherwise go to waste. Draining both breasts more thoroughly also signals your body to produce more, which can be helpful if you’re building a freezer stash or preparing to return to work.
If you notice your baby pulling off, fussing, or gulping during sessions where you’re pumping the other side, the pump’s suction may be triggering a stronger let-down than your baby is used to. Try reducing the pump’s suction level, or switch to a passive collector instead.
Keeping your pump parts clean is important. Wash your hands before handling any equipment. Inspect tubing and flanges for mold or residue before each use. If you’re using a shared pump (like one provided by a hospital or workplace), wipe down the dials, power switch, and surrounding surface with a disinfectant wipe before starting.