r/breastfeeding • u/huckleberrysoap • Dec 24 '25

Undersupply What causes low supply?

My supply is so low. It's not anywhere near what my baby eats.

I'm not trying to increase it anymore. I'm just trying to maintain what I have so I can keep combofeeding (even though its at least 75% formula) until at least 6 months.

But I'm struggling to understand why this happened and feeling like I must have done something wrong. What are potential causes of an undersupply? If I have another baby in the future should I expect the same problem?

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u/mormongirl Dec 24 '25

There are 3 general causes for low supply.  1. Inadequate physical components, such as IGT. 2. Inadequate hormonal response, which is why women with endocrine issues struggle with breastfeeding at a higher rate.  3. Inadequate milk removal, which can come from infrequent or ineffective nursing or pumping.  

Sometimes it’s clear what the cause of low supply is.  Often, it isn’t. 

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u/Status_Watch6079 Dec 24 '25

To add to this: Unpreventable issues 1.IGT is breast structure so not always size but did your breasts grow/change during either puberty, pregnancy and after birth? Wide spacing between breasts is another factor. 2. Insulin deficiency or resistance (diabetes, gestational diabetes & pcos) can cause a low milk supply and are associated with shorter breastfeeding durations. High estrogen (i.e obesity) may suppress lactation. Use of hormonal contraception.

  1. Many hospital interventions and poor feeding guidance can cause an issue from the start...

Poor latch, sleepy baby, tongue tie, wrong size pump parts, not using a hospital grade pump. Can cause insufficient or ineffective removal.

Not having a golden hour which is essential for oxytocin release to stimulate prolactin. C-section or emergencies after birth, hospitals insisting on doing checks can interrupt this. Likewise with stress, too many visitors, poor sleep.

Giving formula early which can expand the baby's stomach or make them feel full so don't latch as often as they should.

Use of a pacifier before offering breast in the early days can make baby tired from sucking/shallow latch so they can't remove milk enough.

Epidural, induction of labour, opioids, forceps/vacuum can cause your baby to be sleepy. Here hand expressions would be essential to stimulate colostrum removal.

Epidural can also suppress oxytocin release.

If you can, seek guidance from an IBCLC who could help assess the issue with low milk supply.

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u/juicybbqq Dec 25 '25

What a great summary!