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Endocrine and Hormonal Reasons You Might Not Know for Low Milk Supply

While there are variety of reasons for low milk supply, endocrine and hormonal reasons are often overlooked.

“Not enough milk” is a frequent refrain from new mothers. In most cases, two explanations leap to my mind. First, is the situation about actually not having enough milk, or just a misperception due to inaccurate information? Or, is the situation of actually having a low milk supply, but it’s due to infrequent removal of milk?

Since those two situations are so common, it’s easy to overlook endocrine and hormonal reasons for low milk supply.

Luteal phase defect

A luteal phase defect is related to insufficient production of progesterone during the luteal phase of the menstrual cycle. (In other words, the phase right after the ovulatory phase.)

This can be a possible explanation for low milk supply.

Sheehan Syndrome

Sheehan Syndrome, discovered in 1937, is a very uncommon condition. It’s due to a massive postpartum hemorrhage. To be clear, I’m not talking about a few soaked sanitary pads. I’m talking about massive bleeding where the pituitary gland has not been perfused with blood. (I will never forget taking care of a young mother who hemorrhaged so much so fast she nearly died.)

Think of the damage in Sheehan Syndrome like you might think of damage from a heart attack. The organ has been deprived of blood, becomes damaged, and isn’t functioning properly. With Sheehan Syndrome, a low milk supply is possible, even probable, depending on how severe the bleeding was.

Sheehan Syndrome may have occurred with a previous birth, but sometimes, the signs and symptoms go unnoticed. So, whether you are the professional or the parent in this situation, carefully review the history from the current, as well as previous labor/births.

Retained placental fragments

Officially, a retained placenta is defined as not having a delivery of the placenta within 30-60 minutes after delivery of the fetus. Those cases are rare, but obvious. However, fragments of the placenta can stay undetected within the uterus for hours — and in rare cases, days, or even weeks. (I’ve seen this.) Serious adverse effects occur.

Copious bleeding, bright red bleeding (“lochia rubra”) after the first 2 days or so (or its recurrence later on) are ominous signs. Similarly, clots, and low milk supply are classic signs of retained placental fragments. In theory, hemorrhage should be the first sign, but sometimes, the first sign can be low milk supply.

Delivery of the placenta triggers withdrawal of progesterone, which in turn, triggers milk supply. If the placenta is not completely expelled, low milk supply will result.


A seldom-mentioned but important condition is Hashimoto’s Thyroiditis. Hashimoto’s thyroiditis is usually classified as an autoimmune disease because the thyroid attacks itself. Nonetheless, it does result in an underactive thyroid. But any cause of hypothyroidism can cause a low milk supply.

Listen as Dr. Jolene Brighten tells of her own experience with hypothyroidism.

Sometimes, mothers who had enough milk in the first 2 months experience a low milk supply around 3 months or so. They blame it on going back to work, or the stress of moving across the country, or some other event. They assure me that their thyroid levels were normal at their routine 6-weeks check-up. I believe them! But I point out how that was several weeks ago.

Especially if hypothyroidism is diagnosed before conception, or if conception was difficult to achieve, a low milk supply around 3 months indicates the need for a thyroid check.

Polycystic ovarian syndrome (PCOS)

Many assume that having PCOS automatically results in a low milk supply. And that is frequently the case. But sometimes mothers who have PCOS will have an oversupply, or a normal supply.

Other endocrine disorders

Here, I’ve addressed only endocrine disorders that seem to be unfamiliar to the people in my courses. But there are many, many endocrine disorders, and any might relate to a low milk supply. And, some conditions, such as diabetes or obesity, are related to the delay of a copious milk supply, but a copious supply occurs later.

Remember, low milk supply has also been linked to hypertension, anemia, and other non-endocrine pathological conditions. So, a thorough assessment by a qualified practitioner is always a good idea.

Have you dealt with a low milk supply? Share your experiences in the comments below!

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  1. Victoria Fisher

    Who would you recommend to go see as far as a skilled practitioner goes to assess for the milk production? Thank you!

    • Marie Biancuzzo

      Hi Victoria. Not to sound like I’m dodging the question, but it really depends on what’s going on. In my experience, most times, low milk supply is due to issues of not completely and consistently “emptying” the breast. (To be clear, just as we all have more urine in our bladders and we all have more tears in our eyes and so forth, the breast is never truly “empty” but hopefully you know what I mean by “emptying” the breast.) So I would start with the “skilled practitioner” who understands the basic physiology of lactation and more specifically, feedback inhibitor of lactation, good latch, verifiable intake (meaning, “mouth on breast” does not equal successful breastfeeding and is often a major factor in not emptying the breast). I’d definitely start there. If the situation doesn’t improve from there, I’d seek someone who can take an excellent history of what’s going on. In an ideal world, that would be lactation consultant, but honestly, not everyone who has certification or titles actually knows how to do this. Find someone who has many years of experience and ideally someone who has been in private practice for several years with recommendations from past clients. Such a “skilled practitioner” should know the difference between some physiologic reasons (which almost always boil down to issues with FIL) before you go chasing pathologic reasons with medical management. It’s certainly possible there’s an oddball explanation such as some of the examples I’ve given in this post — and if that appears to be the case, then lab work (blood tests) would be the next line of inquiry to pursue. So this was a long-winded way of saying, in my experience, about 80% or more of the “not enough milk” is due to either a matter of perception, OR a physiologic explanation for it. Relatively few of the cases are due to pathologic reasons (some hormonal or endocrine dysfunction that requires medical management or some other type of intervention.) Hope that helps.

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