As a pumping momma, I watched every ounce and I got stressed if I saw even half an ounce less than I expected. So why do we pump different amounts of milk… and why might we suddenly be making less milk?
Note: We are exploring why supply might decrease from where it once was… not why a momma might have low supply in the first place.
Additional note: This blog was written by an exclusive pumper for exclusive pumpers, but can benefit any momma who pumps. As an exclusive pumper, it’s easy to obsess over milk supply. It’s also often more noticeable when we make more or less milk, since we are doling it out to bottles, bagging it, freezing it, and managing pumped milk on a daily basis. It might not be as easy for a nursing momma to realize their milk supply has decreased. If you are concerned, please speak with a lactation professional.

Factors that can reduce milk supply temporarily
The following may result in lowered output per session or per day.
- Clogged/inflamed milk duct (Milk can get trapped within the breast and not be able to easily pass through the duct)
- Off-centered flange (Totally makes a difference! Check to make sure they stay centered- a well-fitting flange will stay centered better than a flange that is too large.)
- Dehydration (This is less of a “goal number of ounces” and more of a reminder to stay hydrated throughout the day)
- Not eating (It’s hard to remember to eat sometimes, especially as a new momma!)
- Time of day (milk can be lower in the evening and higher in the wee hours of the morning)
- Skipping a pumping session (Your body will take protective measures to reduce output if your breasts aren’t continually emptied.)
- Stress (High levels of stress can negatively affect milk supply, and/or can affect letdown.)
- Fatigue (I know you don’t want to hear it, but try to get some sleep when you can, momma!)
- External pressure (Tight bras/stomach sleeping)
- Internal pressure (Engorgement/clogs)
- Worn or damaged pump parts (Replace your valves!)
- Heavily used pump (Could your pump be losing power?)
- Certain medications (like decongestants)
- Sickness (especially gastrointestinal illness)
Factors that can reduce milk supply more permanently
The following may result in lowered output overall
- Mastitis (Again, a protective measure your body takes. Unfortunate but true!)
- Repeatedly skipping pumping sessions (Once or twice usually won’t have a lasting effect. Try not to make it a habit!)
- The return of your period (Some mommas see a reduction only during their period, some see an overall reduction.)
- Starting birth control (especially one containing Estrogen, but any fluctuation in hormones can affect supply.)
- Supplementing with formula instead of pumping (Less demand = less supply)
- Consistent use of secondary pump (For example, if a wearable pump does not empty you well, save it for occasional use only.)
- Chronic (ongoing) stress
- Chronic fatigue
- Ongoing/high levels of smoking/drinking/caffeine intake

Look for correlations
A correlation is when variables move in relation to each other. For example, when I pumped 3 ounces instead of 5, I thought, “Melissa… have you drank any water today?” The answer was usually no. (I can go hours and hours without thinking to drink. It’s a problem.) While correlation doesn’t allllways equal causation, dehydration most definitely caused my supply to temporarily decrease. Conversely, I found that I’d pump a bit more milk after eating a big cheeseburger. Protein/calories and hydration had a big effect on my output.
If your pumping session yields less than you expected, I encourage you to think back on the previous 12 hours or so… Were you stressed? Did you eat? Could you be dehydrated? Are you sick? Have you skipped a session? Did you get sleep? Etc. Try to find a correlation that might explain the lower output.
Getting back on track
If you can identify one or more of these factors that could be causing your reduced supply, focus on reversing that impact and getting back on track. Here are a few examples:
- Did you skip a session? Set an alarm or rearrange your schedule to prioritize pumping.
- Did you forget to eat or drink until afternoon? Have some easy to grab snacks and a water bottle or glass on hand where you spend most of your time. Prepare food while baby is sleeping or occupied, or have your partner help you prepare food so you make sure you get those extra calories and stay hydrated!)
- Had the stomach bug? Rest, Focus on sipping fluids, add electrolytes, and regain your usual diet when you can keep food down! Some mommas even pay to get IV hydration!
- Forget and take Sudafed? Discontinue use and talk to your doctor about what medications might work better for a breastfeeding mom.
- Has your period returned? Check out my blog for more tips concerning your monthly cycle and its effect on milk supply.
- Not responding well to your pump? Check your flange size, replace your valves, and see if another style pump (even a manual pump!) could empty you better, yielding more milk.

What if your milk supply continues to decrease?
Sometimes milk supply decreases and stays decreased, despite everything within our control.
- Speak to a lactation professional that specializes in low supply
- Supplement with pumped breastmilk
- Supplement with formula
- Increase solids, when you are able
Remember, your worth isn’t measured in ounces. A fed baby is a happy baby. Just because your baby isn’t getting 100% of your breastmilk doesn’t mean they aren’t getting 100% of the benefits of your breastmilk. Every drop counts.

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