How much milk should I be expressing?

This blog is written by Lauren Brenton from One Mama Midwife

If you've spent any time on social media while pregnant or newly postpartum, you've probably seen it. A photo of a fridge shelf lined with full bottles, or a freezer stash so big it takes up the whole freezer drawer. If your own pumping sessions are getting a fraction of that, it can be easy to spiral into thinking something is wrong with your supply.

I want to unpack this properly, because the research on this is clear and honestly quite reassuring.

Breastfeeding runs on supply and demand

The most important thing to understand about milk production is that it works on supply and demand. The more effectively and frequently milk is removed from the breast, whether by a feeding baby or a pump, the more your body is signalled to make. This is why early initiation of breastfeeding and frequent removal in the early weeks matters so much, and why skipping feeds or sessions can cause supply to dip.

But here's the part that trips people up. A baby who is breastfeeding directly is extremely efficient at removing milk. So, when you switch to expressing, especially if your baby is still doing most of their feeding at the breast, you are often only collecting the milk left over after a feed or milk expressed in between feeds when supply hasn't fully replenished. A smaller amount in the bottle doesn't mean a smaller supply. It usually just means your baby already got exactly what they need.

What does the research actually say is normal?

This is where some of the most important work in this field comes from right here in Australia, out of the University of Western Australia's lactation research group. They used ultrasound imaging and their studies found that a woman's breast storage capacity, meaning how much milk the breast can comfortably hold between feeds, can vary up to three times between individual women. Crucially, this has nothing to do with breast size. A smaller breast with more glandular tissue can outproduce a larger breast with more fatty tissue.

What this means practically is that two women exclusively breastfeeding a similarly aged, similarly sized baby can pump very different amounts, while both making healthy amounts of milk. Kent's research also measured total 24-hour milk production in exclusively breastfeeding mothers and found it ranged from roughly 478 mL to 1,356 mL a day — a wide but entirely healthy spread, regardless of how that milk is distributed across sessions or how much shows up in a bottle at any one time.

The Australian Breastfeeding Association reflects this in their guidance too. If you're breastfeeding directly and expressing occasionally, it's entirely normal to pump somewhere between 15 and 60 mL in a session. Some mums get more, some get less, and neither is a red flag on its own. Their advice is blunt and I love it for that: don't judge your milk supply by how much you can express.

Exclusive pumping has different expectations

If you are exclusively or predominantly expressing rather than feeding at the breast, larger volumes are more realistic, because the pump is now doing all the work the baby would otherwise be doing, multiple times a day. Even here, though, a Western Australian study of predominantly pumping mothers found that this group has historically been poorly understood in the research, despite being a growing population. This study found that exclusive pumping itself did not negatively impact 24-hour milk production or the amount of milk available to the baby, when supported properly. So if you are choosing to exclusively pump and bottle feed your baby or this is the option that works for you, please know that you're not doing something that may be detrimental to your supply; you're just working with a different removal method that has its own learning curve but still works on supply and demand.

So why do some people get those huge bottles?

A few reasons and none of them mean you're doing it wrong if it's not your reality. Some women naturally have a larger storage capacity. Some are exclusively pumping and therefore expressing everything their baby needs across the day, not just a top-up. Some are further along in an oversupply pattern, which comes with its own challenges. And some are simply showing you their best session, not their average one. Comparing your in-between-feed top-up to someone else's entire day's exclusive pumping output is comparing two completely different situations.

Where the E-Ladybug fits into the postpartum picture

This is exactly the kind of context I wish every new mum had before she started expressing, because it changes what you reach for and why. The Haakaa E-Ladybug is a small, wearable electric pump, and its usefulness in the postpartum period comes down to fitting realistically into how supply and demand works and what life is like with a baby (and multiple children if you’re like me).

For most breastfeeding mums, the goal isn't to replace a feed with a pump session; it's to collect a little extra whether that's to build a small stash for an outing, share a night feed with a partner or to simply relieve fullness. A lightweight, hands-free pump like the E-Ladybug is genuinely what I use for this, because it means expressing doesn't have to mean sitting trapped to a machine for twenty minutes. You can express while you're doing bath time, cooking dinner, or having five minutes to yourself, which in the postpartum period is worth more than people realise.

It also takes some of the pressure off. I would much rather do lots of little pumping sessions when I need it rather than trying to sit and stress over what amounts I am able to get out over bigger expressing sessions and feeling deflated when it doesn't match a stranger's freezer stash online. And little and often, as the research above shows, is exactly how supply and demand is meant to work.

Remember, your body isn't underperforming because your bottle looks different to someone else's. Milk production is so individual, shaped by storage capacity, feeding pattern, and how milk is being removed, and the Australian research on this is unambiguous that pumped volume is not a reliable measure of supply. Understanding supply and demand is what is important for your milk production and your mental load in those early months.

Written by Lauren Brenton
Endorsed Midwife, Founder One Mama Midwife & Mum of 5

Important information: This article is provided for general information and education only. It is not personalised medical advice, diagnosis or treatment, and is not a substitute for care from a qualified health professional. If you have concerns about breastfeeding, expressing, milk supply, infant feeding or your baby’s growth, please speak with your midwife, GP, Well Child Tamariki Ora provider (NZ), child health nurse (AU) or an International Board Certified Lactation Consultant (IBCLC). Never disregard professional medical advice or delay seeking it because of something you have read here.

Always use Haakaa products in accordance with the instructions and safety warnings supplied with the product.

References

Australian Breastfeeding Association. Expressing – the basics.

Gridneva, Z., Warden, A. H., McEachran, J. L., Perrella, S. L., Lai, C. T., & Geddes, D. T. (2025). Maternal and Infant Characteristics and Pumping Profiles of Women That Predominantly Pump Milk for Their Infants. Nutrients, 17(2), 366.

Kent, J. C., Mitoulas, L. R., Cox, D. B., Owens, R. A., & Hartmann, P. E. (1999). Breast Volume and Milk Production During Extended Lactation in Women. Experimental Physiology, 84(2), 435–447.

Kent, J. C., Mitoulas, L. R., Cregan, M. D., Ramsay, D. T., Doherty, D. A., & Hartmann, P. E. (2006). Volume and Frequency of Breastfeedings and Fat Content of Breast Milk Throughout the Day. Pediatrics, 117(3), e387–e395.

Geddes, D. T., Gridneva, Z., Perrella, S. L., Mitoulas, L. R., Kent, J. C., Stinson, L. F., Lai, C. T., Sakalidis, V., Twigger, A.-J., & Hartmann, P. E. (2021). 25 Years of Research in Human Lactation: From Discovery to Translation. Nutrients, 13(9), 3071.