What causes oversupply and undersupply?

As in, what differences are there physiologically between women who produce too much milk and women who don't produce enough? Can somebody explain it to me? If it's just a case of hormones, why doesn't it always work to give them medication? If it's supply and demand, why doesn't it always work to have baby or pump on the breast more often? What exactly differs between high supply and low supply, and why can't it always be corrected?

I've had oversupply for the most part with both my girls. Even when pregnant, I could sit there for 30 minutes and hand express 20ml of colostrum no worries. What is it about my makeup or body that can't be chemically replicated for women who aren't producing? What is it about their bodies that they have trouble producing enough milk, and why isn't there an 'easy' fix for that?

Sorry if they're kind of daft questions, just pondering.

Ive wondered the same!

I can only speak from my experience of under supply. I have hyperplasia - lack of breast tissue which means I can't produce enough milk. The lactation consultant told me it was like only having a shot glass instead of a big mug - even though it keeps "refilling" by supply and demand, there isn't enough milk to nourish a baby. And nothing can increase the quanity of breast tissue, so there isn't much that medication can do. I take motilium to help me produce as much as possible, but it is still not enough given the physical limitations.

Thanks Bloom, that's the kind of thing I was wondering about. Do you know how common it is? I assume there's no way to correct that, lack of tissue is lack of tissue huh?

I think there is a complex interplay of hormones too. Prolactin would be inhibited by other hormones so it might depend on other factors such as weight, age etc. I know I have high prolactin because I have always struggled with over supply. I haven't had a period since before dd (going on 5 years) and so I clearly have low levels of other hormones.

no idea about the undersupply but i was told that the more babies you have the more glands or whatever it is you produce and so if you already have oversupply you generally, with each kid produce more and more milk each time...i was like :o but i already have too much milk LOL!

I believe several of the important factors have been mentioned above - amount of glandular tissue, storage capacity, frequency and efficacy of milk removal and hormones. It's multifactorial, complex.

I think the bottom line is no one can explain it all and the causes will vary from situation to situation so there's not a one size fits all fix.

I too have undersupply - through surgical removal of breast tissue and severance of the ducts as part of breast reduction surgery. Hormonally I am pretty normal, but I too have the 'shot glass' - I just can't make any more than I do now. Although I take motilium, because my hormones are normal, it may not actually be doing much to help. It's hard to know for sure, so I just keep taking it.

Like all complex human systems, everyone is a bit different, and although *most* women adjust supply perfectly according to demand, of course there will be differences between women, ad some will have a dysfunction associated with any of the many different steps and linkages and processes involved.

I read an article recently that said something along the lines of 'there is no other human function in which all individuals are expected to be able to perform perfectly, every time. We don't tell patients with asthma/impotence/diabetes that everyone else can run a marathon/keep it up/produce enough insulin, so they should be able to as well. But we tell women with lactation issues that they should be able to breastfeed normally'. The trouble is, we (scientists) don't know enough about it yet.

There may be physiological differences between women in regards to the amount of glandular tissue and effectiveness of hormone production, but there are other environmental factors as well. Plus, these things can change - women grow more glandular tissue with subsequent pregnancies, for eg.
Frequency and effectiveness of milk removal in the early weeks impacts the ability of your breasts to respond to the hormones necessary to produce milk as prolactin receptors are laid down at this time.
It's a good question! And it would be very good to be able to answer these things definitively. Let's hope things will be easier for our girls.

I find it really fascinating. Especially with how much we now know about the human body, it surprises me that something as important and breast milk production seems to be left behind a little. MadB I agree, I hope by the time out children are grown, it's clearer and easier for them.

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If it's supply and demand, why doesn't it always work to have baby or pump on the breast more often?

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I think on this front either the baby or the pump could be not effective so the 'demand' might not be happening even though the baby or pump is there all the time. Examples of this would be poor attachment, tongue tie, sleepy baby, pumps just being pumps and not being 100% effective. If you can't get a good attachment and a pump isn't cutting the mustard you are kind of screwed cause there is no other way of generating a good 'demand'.

I remember a woman at my mothers group who during our 2 hour session fed her DS 4 or 5 times. It turned out to be a tongue tie which was fixed eventually (like when he was 4 months old or something) but up until then he just couldn't attach properly, so would only get a small amount, then get hungry 30 minutes later. God knows what made her keep going until it god fixed, the woman must had had the patience of a saint and not like sleep! Anyway she was never getting to the totally empty breast stage which is very crucial in creating the 'demand'. So even when it did get fixed she had already missed a lot of the early establishing supply weeks and I guess you would say the feeding to boost supply was a lot less effective once the body had already had 4 months of getting the 'no you don't need to make any more milk' message.

There could be a book on this, possibly a bit too much to sift through on a web forum, but I can try! Primary lactation failure occurs in probably about 1-3 percent of lactations. It’s hard to get a good figures, because there are lots of mums that can’t breastfeed, but more often than not it’s caused by the general stuff-up around birth and lack of knowledge in our culture. Diana West and Lisa Marasco’s “Making more Milk” is fabulous, and gives information on oversupply as well.. When you are looking at causes of low milk supply you are looking at

- Baby causes (ie a baby that can’t attach and remove milk from the breast due to prematurity, birth injury, tongue tie, separation, problems with palate.
- Then you have mother issues - there are a small number of medical conditions that cause mother not to have enough milk - hyper or hypo thyroid, pituitary, lack of glandular tissue in the breast (hypoplasia) which may in the first place been caused by hormonal problems, or retained placenta (the placenta produces progesterone, which prevents the milk making hormone prolactin doesn’t work effectively to make milk. Lack of feeding (ie spaced feeds or separation of mother and baby) may mean that prolactin levels which should be high after the birth don’t peak, or reduce quicker than normal. We could test for this (but few health professionals would know what they were looking at.)
Generally speaking, oversupply is easier to manage. Most mothers oversupply when their milk comes in. At this time their milk supply is driven by high levels of prolactin. Over time their prolactin levels reduce to a fairly normal level (maybe 10% above their pre-pregnant level), but the thing that governs their supply is the baby feeding. So most people find that their milk adjusts over time to meet the needs of their baby.
Things liked timed feedings - waiting for 3-4 hours to elapse before feeding the baby exaggerates symptoms of oversupply, wheras if baby was feeding more frequently, slept with it’s mum and fed at night many women would not become overfull. some oversupply is hormonally driven as well.
The good news is despite any of these things most mothers can breastfeed. In a case of low supply, nearly all mothers can breastfeed, even if not fully breastfeed. And given that I am a glass half full person I think that’s fabulous. The hard thing is it’s normal to want the full experience and all the benefits it brings for you and your baby and it hurts like heck when it doesn’t happen. And no-one understands - they just look straight through you with an attitude of “just put your baby on the bottle and get over it”. Generally, when mothers don’t make a full supply, it’s a combination of factors. If it was just one thing we’d work it out a whole lot more easily! Have a look at the making more milk book or the website www.lowmilksupply.org
Whether you have oversupply or undersupply - see an LC or breastfeeding counsellor. Even when you think “you’ve done everything” they have more tricks and information. Breastfeeding is worth doing, and its worth working through your problems.

On a *slight* side-tracking and picking up on the retained product affecting supply...

I have only *just* passed some retained placenta and this could maybe explain my DD3s issues with BF? I have always had huge oversupply with all my girls, but this time it just feels as though my breasts never adjusted post birth. I am always full and during feeds have several let-downs?? I am also still spraying through tops and cannot even touch around the breast area without serious milkage (eeep!). could the RPOC be why this is still so funky?

And now that my RPOC has passed (well we are plenty certain it has), could this be why she is again struggling with my milk? just noticed in teh last few days that she has been really upset at the breast for each feed? could it be changing and causing some discomfort or something for her? It has been playing on my mind that is all....

Cassius funny you should mention it as I had similar issue with my supply this time after that aswell unless it is a coincidence. But hard to tell as I was/am tandem feeding as well.