Why does breast milk have bubbles when pumping? Plus 12 more weirdly specific Google searches, answered

For those navigating the world of pumping, questions pop up by the minute. I know for me, across two breastfeeding journeys, my search history was awash with the strangest questions and notions. I also know, I was not alone. Someone, somewhere out there, will be searching for the same thing, I guarantee it. 

Whether you’re wondering about bubbles, milk storage, why breastmilk looks so watery, or the best way to sit while pumping, we’ve teamed up with award-winning breast pump brand, Cimilre to tackle some of Google’s most searched questions on the topic.

Let’s go!

Why does breast milk have bubbles when pumping?

If you notice bubbles in your pumped milk, there are a few potential reasons:

• Natural composition: The process of pumping can introduce air into the milk, creating bubbles. This is normal and doesn’t impact the milk’s quality.
  
• Loose connections: Check that all parts of your breast pump are properly assembled and fitted to prevent air leaks.
  
• Soap residue: If pump parts aren’t thoroughly rinsed after cleaning, lingering soap can create bubbles in the milk.
• Forceful letdown: When milk is released very quickly from the breast, it is pulled into the pump just as quickly, which may cause more air bubbles than with a slower letdown.
  

Bubbles typically settle after storage, but if they persist, it might be worth troubleshooting your pump setup and ensuring all pump parts are washed and rinsed thoroughly. A visit with a lactation consultant while pumping can also be helpful to determine your unique situation.

Can I combine pumped breast milk from different days?

Yes, but it’s important to follow safe storage guidelines (we’ve put together a super-helpful storage guide for you to pin and refer to):

• Freshly expressed to refrigerated: The CDC recommends cooling freshly expressed milk before combining it with already cooled, refrigerated milk, to maintain a consistent temperature. It’s important to also consider the date milk was pumped.

When combining milk from different days, consider the first day of expressed milk for the duration of storage. For instance, if you have milk pumped from yesterday that you are combining from today’s pump, consider everything as pumped from yesterday.

• Freshly expressed to room temperature: When adding freshly expressed milk to milk that’s already at room temperature, the total time is based on the oldest milk. 

So, if you add new breast milk to milk pumped three hours ago and left out at room temperature, the entire container, including the freshly expressed breast milk, is now three hours old. While breastmilk can be left at room temperature for up to 4 hours, it is recommended to place it in the refrigerator if it will not be used within a few hours, especially for those of us living in warmer climates.

• If you have a medically fragile baby, check with your healthcare provider for the most up-to-date advice for your unique situation.

What’s the best way to sit while pumping breast milk?

When it comes to pumping, your comfort really matters! Here are some top positioning tips:

• Sit upright, with your back comfortably supported, shoulders rolled back, feet on the floor, and arms resting easily.
  
• If recovering from a c-section, a slightly reclined position with pillows can help relieve pressure.
• Ensure proper flange, bottle, and backflow protector placement to avoid discomfort and maximize milk output. The flange should be centered around the nipple, using the correct size breast shield.

Can I start pumping breast milk before giving birth?

It depends on your individual situation. In most cases, pumping before your baby is born isn’t recommended unless your doctor specifically advises it. That’s because nipple stimulation from pumping can trigger contractions, which may not be safe during pregnancy, especially if you’re at risk for preterm labor.

That said, some parents are encouraged to collect colostrum (the nutrient-rich first milk) in the final weeks of pregnancy, especially if there’s a medical reason – like a planned C-section. But this should always be done under the guidance of your healthcare provider or a lactation consultant, to make sure it’s safe for you and your baby.

Why does my pumped breast milk look watery, and how can I fix it?

Breast milk naturally varies in appearance due to fat content. Some key points here to bear in mind:

• Breast milk is not as homogenized as cow’s milk, meaning fat separates over time. This is why you may see a fat plug – or layer of fat – on top of the milk after it has been sitting.
  
• Fuller breasts produce lower-fat milk, while emptier breasts have a higher fat content. Fat content gradually increases as the breast is emptied.
• Foremilk, or milk your baby gets when they first start feeding, appears more watery than hindmilk, the milk your baby gets towards the end of a feed. With longer time between feeds or pump sessions, foremilk may appear more watery.
• Frequent and thorough emptying of the breast can increase fat content. The longer milk sits in the breast, the more watery foremilk you’re likely to express. Regular, complete emptying helps reach the fattier hindmilk and encourages overall higher-fat production.
• It’s completely normal for breast milk to separate while being refrigerated. If your milk appears watery, give it a gentle swirl before feeding.

Why does one breast produce less milk when I pump?

It’s common for one breast to produce more milk than the other – this is often referred to as having a “slacker boob”. A kinder way of thinking about it is that your breasts are sisters, not twins! 

Studies show up to 90 percent of breastfeeding parents experience this natural imbalance, with as many as 65.7 percent producing more on the right side. TRB editor Jessie Day notes that for her, it was actually her left side which produced more milk when pumping, however, and it really is unique to every individual. 

Looking to boost milk production on your slacker boob? Use our team cheat sheet:

• Use a dual-motor breast pump (like the Cimilre S7 Dual Pro) to control suction individually on each side.
• Consider hands-on pumping. Gently massage and apply compression while pumping to maximize milk output and empty breasts fully.
• Add an extra session or extend pumping time on the slacker side (keep reading for more details on power pumping) which can also be helpful to bring your boobs up to speed.

Does breast milk pumped at night contain melatonin?

Yes! Studies show that breast milk contains higher melatonin levels at night, which may help regulate your baby’s sleep-wake cycle. 

Your body actually adjusts the composition of your milk based on the time of day – and at night, melatonin levels go up. Melatonin is the hormone that helps signal to the body that it’s time to sleep, so this nighttime milk may play a role in helping your baby settle down and start to develop a natural sleep-wake cycle (aka their circadian rhythm).

If you’re pumping, it can be helpful to label your milk as AM or PM. Offering that PM milk during evening or overnight feeds might give your baby a little extra sleepytime support – especially in those early months when sleep feels like a wild ride. Nature’s sleep aid, straight from you.

How many calories do I burn while pumping breast milk?

Pumping burns between 500-700 calories per day. Remember, burning calories is not the same thing as weight loss – top priority should be giving yourself and your body grace at this time.

What is power pumping, and how does it increase milk supply?

Power pumping mimics cluster feeding to stimulate supply. A typical session might look like:

• Pump for 20 minutes
  
• Rest for 10 minutes
  
• Pump for 10 minutes
  
• Rest for 10 minutes
• Pump for 10 minutes

This method can help signal the body to increase production over time.

How do I safely pump and dump breast milk?

La Leche League states that pumping and dumping is not necessary for alcohol consumption.

Instead, wait 2-3 hours per standard drink before feeding. If you have medical concerns requiring milk disposal, consult your doctor.

Does pumped breast milk still contain antibodies?

Yes! Pumped breast milk has the same nutritional composition as when you’re breastfeeding.

So even when expressed, breast milk retains its immune-boosting properties.

Should I discard pumped breast milk if it contains blood?

While seeing blood in breast milk can be alarming, it is typically harmless. Causes may include:

• Cracked nipples
• Broken capillaries from suction
• Rusty pipe syndrome (a temporary issue due to increased blood flow in early lactation)
  

If the issue persists, speaking with your healthcare provider or a lactation consultant can help determine the cause.

Can you over-pump breast milk?

Yes! Over-pumping can lead to oversupply. 

Oversupply, when you produce more milk than your baby eats, can lead to engorgement, clogged ducts, and discomfort. If you’re trying to build a freezer stash or manage supply, it’s helpful to consult a Certified Lactation Consultant (CLC) to create a pumping plan that meets your needs.

Need a pump upgrade?

To help you have control over your breastfeeding journey, Cimilre offers a range of innovative, adjustable breast pumps on their website and on Amazon. They are also available through insurance (check eligibility by region to get started). 

The award-winning S7 Dual Pro Rechargeable is our top pick right now, giving you ultimate control over your pump sessions with dual motors and adjustable cycle speeds and suction strength.

For more go-to breastfeeding and pumping resources, put these handy guides on your reading list:

• Breastfeeding in the NICU (& preemie pumping) – keep this fact sheet
• Breast milk nutrient composition – all gain – what’s actually in your breast milk (& how can you go for gold?)
• CDC Breastfeeding Guidelines – including breast milk storage questions & answers

Happy pumping!