IGT stands for insufficient glandular tissue, a condition where the breast does not develop enough milk-producing tissue to generate a full milk supply. Unlike most causes of low supply, which can be corrected with better latch, more frequent feeding, or pumping, IGT is a structural issue. The breast simply doesn’t contain enough of the glands that make milk, and no amount of nursing technique will fully close that gap.
How IGT Differs From Other Supply Problems
Most breastfeeding challenges involve a delay in milk coming in rather than a permanent limitation. Being a first-time parent, being over 30, having gestational diabetes, or having polycystic ovary syndrome (PCOS) can all slow the process. But once those temporary hurdles are addressed, supply typically catches up. IGT is different. It falls into a much smaller category of conditions, alongside breast reduction surgery, where a full milk supply is unlikely regardless of effort or technique.
This distinction matters because parents with IGT often spend weeks or months trying every tip, supplement, and pumping schedule they can find, believing they’re doing something wrong. Understanding that the issue is biological, not behavioral, can be both clarifying and relieving.
Physical Signs of IGT
There is no single blood test or scan that definitively diagnoses IGT. Instead, lactation consultants and physicians look for a cluster of physical characteristics that suggest the breast tissue didn’t fully develop. The most recognized markers include:
- Wide spacing between the breasts. A gap of 1.5 inches (3.8 cm) or more between the breasts, caused by underdevelopment of the inner portion of the breast.
- Significant breast asymmetry. A difference of two or more cup sizes between breasts, not just the slight unevenness most people have.
- Little or no breast growth during pregnancy. Most pregnant people notice at least one cup size increase. With IGT, breasts may not change at all or change very little.
- No breast fullness after birth. The engorgement or heaviness that typically arrives in the first week postpartum may be absent, suggesting the tissue needed to activate milk production isn’t there.
- Tubular or elongated breast shape. Breasts that are narrow at the base and bulge primarily at the areola rather than filling out evenly.
In a survey of women who reported insufficient milk production, 72% experienced little or no breast growth during pregnancy, about 47% had widely spaced breasts, and roughly 68% had at least one atypical breast shape. Not every person with IGT will show all of these signs, and having one marker alone doesn’t confirm the condition. It’s the combination, especially paired with persistently low supply despite good breastfeeding management, that points toward a diagnosis.
What Causes It
IGT originates during breast development, which happens in stages: puberty, pregnancy, and the early postpartum period. At any of these stages, hormonal disruptions can interfere with the growth of milk-producing glands. The breast ends up with more fatty tissue and less functional glandular tissue than it needs.
Hormonal conditions play a significant role. PCOS, which affects 5% to 10% of women of reproductive age, is one of the most commonly linked conditions. Insulin resistance, a feature present in 35% to 80% of women with PCOS, appears to interfere with the hormonal signaling that drives breast tissue development during puberty and pregnancy. Thyroid disorders, elevated androgens (male-type hormones), and other endocrine imbalances have also been associated with underdeveloped glandular tissue. In some cases, though, no underlying hormonal cause is ever identified.
How IGT Is Identified
Diagnosis typically happens after the baby is born, when a parent struggles with supply despite doing everything right. A lactation consultant will assess breast shape and spacing, ask about changes during pregnancy, and evaluate how much milk the baby is actually transferring during feeds. Weighted feeds, where the baby is weighed before and after nursing on a precise scale, can help quantify how much milk is being produced.
Some parents recognize the signs earlier. If your breasts didn’t change during pregnancy and you notice several of the physical markers described above, raising the topic with a lactation consultant before delivery allows you to plan ahead rather than scramble in the stressful first days postpartum.
What Helps (and What Doesn’t)
IGT can’t be “fixed,” but the amount of milk you do produce still matters and can often be maximized. Frequent nursing or pumping in the early days helps stimulate whatever glandular tissue is present. Some parents with IGT produce a partial supply, covering anywhere from a small fraction to a majority of their baby’s needs.
Medications called galactagogues are sometimes used to boost supply. The strongest evidence exists for domperidone, a drug that raises prolactin levels. In several controlled trials, mothers taking domperidone saw meaningful increases in daily milk volume compared to placebo groups. One study found output nearly doubled over two weeks, and another showed 76% of the treatment group reached a target milk volume versus 22% on placebo. Results vary, and these studies were conducted in mixed populations, not specifically in people with IGT. When the underlying issue is a lack of glandular tissue, medication can help the existing tissue work harder but can’t create tissue that isn’t there.
Metformin, often prescribed for insulin resistance, has been explored as a potential option given the PCOS connection. However, trial results so far have not shown a significant effect on milk volume.
Feeding Your Baby With IGT
Most parents with IGT end up combination feeding, meaning they breastfeed what they can and supplement the rest with formula or donor milk. A supplemental nursing system (SNS) is one practical tool that makes this easier. It’s a small container of supplemental milk worn around your neck, with a thin tube taped alongside the nipple. The baby nurses at the breast and receives extra milk through the tube at the same time. This lets you maintain the breastfeeding relationship and continue stimulating your supply while ensuring your baby gets enough to eat.
Other parents alternate between breast and bottle, or pump and supplement. There’s no single right approach. The goal is a well-fed baby and a feeding routine that feels sustainable for you.
The Emotional Side of IGT
An IGT diagnosis often comes with grief. Many parents feel their body has failed them, especially in a culture that frames breastfeeding as something that should “just work” if you try hard enough. The emotional weight is real: maternal stress, anxiety, and depression are linked to breastfeeding difficulties, and the relationship runs both ways. Struggling to feed your baby increases distress, and that distress can further suppress the hormonal pathways involved in milk production.
Finding support from other parents with IGT, whether through online communities or local groups, can help counter the isolation. Working with a lactation consultant who understands IGT is equally important, because generic breastfeeding advice (“just nurse more”) can feel invalidating when your body has a structural limitation. A knowledgeable consultant will focus on maximizing what your body can do while helping you build a realistic, guilt-free feeding plan.