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Mammary Hypoplasia/IGT: What is it and what do you do if you’re diagnosed

Breast development begins before you are even born. It continues through several stages during puberty, childbearing years, and beyond. Breasts never stop changing. Hormones signal changes during puberty, pregnancy, and after the baby is born for an intricate system inside the breast for milk storage and transport to be able to feed your baby. 

All breasts are unique in size and shape. 


Having small A cup breasts is not a predictor that you will have a low milk supply, just like having large breasts doesn’t mean you will have lots and lots of milk. 


Milk production is based on your anatomy including the development of your breast’s ductal system and nerve pathways, milk storage capacity, hormones, and hormone receptors, and effective and frequent milk removal.

Reasons for low milk supply

  1. Pre-glandular - reduced supply is caused by hormone imbalances caused by a retained placenta after delivery or postpartum thyroiditis.
  2. Glandular - could be due to a prior breast surgery that severed mammary ducts or important nerves or hypoplasia/IGT (Insufficient glandular tissue). Often, there will be pre-glandular or post-glandular markers as well contributing to the picture.
  3. Post-glandular - when breastfeeding got off to a tough start or issues with the baby being able to transfer milk well due to oral restrictions, birth trauma, or other complication. Separation from your baby after birth and other breastfeeding management factors like scheduled feeds, introduction of supplements, early pacifier use, and sleep training can negatively affect milk supply.

Breast development

In utero, breasts begin to form along the mammary ridge on the chest. By birth, nipples have formed and the beginnings of a ductal system are in place. 

Puberty, driven by the ovaries releasing estrogen, causes breasts to grow as fat begins to build up and the ductal system grows as glands form at the end of the milk ducts.(1) As puberty continues, with the release of estrogen in the first half of the menstrual cycle more lobules and ducts grow followed by the second half of the menstrual cycle when progesterone stimulates the formation of milk glands. 

Pregnancy & birth trigger the lactation process. During pregnancy, starting around 16 weeks, your hormones send the message for milk ducts to multiply.(2) Changes to your areola and breast size and appearance happen during pregnancy and after you deliver your baby and the placenta. 

Alveoli are small sacs that make and store milk. Clusters of alveoli are called lobules which make up a lobe. Each lobe is connected to a duct. Ducts are a network for milk to flow through towards the nipple when a baby begins to suck. There are lots of sensitive nerve endings in the areola. When they are stimulated by your baby's sucking, hand expression, or pumping, oxytocin is released and milk flows. Prolactin is also released which sends the message to make more milk as it is removed. Damage to the nerves can affect sensation, milk release, and milk production.

What is hypoplasia/IGT?

Hypoplasia is a condition in which a person’s glandular tissue develops differently. It is characterized by breast shape, the distance between each breast, and symmetry. Not all people with hypoplasia have lowered milk supply, but it is more common. Management techniques can help increase supply. If you have hypoplasia/IGT, you can still have a satisfying nursing relationship with your baby.(3)

Signs of hypoplasia/IGT(4)

  • Normal-sized breasts that lack a sufficient amount of glandular tissue often result in reduced milk supply
  • Breasts are widely spaced apart
  • One breast is much larger than the other - breast asymmetry
  • Breasts have stretch marks without them growing larger. This may appear during puberty or pregnancy.
  • Breasts are tubular-shaped
  • Areola has a swelled or bulbous appearance and is large compared to breast size
  • No noticeable changes to breast size or feelings of fullness during pregnancy or postpartum
  • No noticeable veining in the breasts increasing during pregnancy

Maximizing milk supply & nursing with hypoplasia/IGT

Hormones play an important role in glandular development, milk production, and supply. Polycystic Ovarian Syndrome (PCOS) and insulin resistance sometimes accompany IGT. Not everyone with PCOS and insulin resistance have IGT and may develop sufficient glandular tissue and have a full milk supply. 

Black cumin seed, in Pump Princess, is a powerful hormone-balancing herb used to regulate thyroid hormones, raising T3 and T4 while lowering TSH.(5) People who have experienced issues with low supply previously, have a history of PCOS, insulin resistance, and hypothyroid may find Black Cumin seed helpful when they are trying to increase their milk supply. 

Goat’s rue contains a compound called genistein which is shown to increase breast tissue and milk storage capacity. People who did not experience growth of their breasts during pregnancy as well as those who had a rocky start and their milk storage decreased, reducing supply, can benefit from Goat’s rue. Legendairy Milk’s LechitaLiquid Gold, and Cash Cow all contain Goat’s rue.

Breastfeeding is partly about milk for your baby, but there is so much more to a breastfeeding relationship that can be enjoyed regardless of IGT. When hormone issues and breastfeeding management are being addressed and supply is still low, IGT may be the resulting diagnosis. 

After the baby is born, being skin to skin sets up mom and baby for a good start to nursing. Interruptions and separation from each other interfere with how often the baby nurses. Frequent and effective milk removal will send the signal to keep making milk.

Using a supplementer at the chest is a popular tool where all feeding takes place at the breast. The baby will get all of the mom’s milk while feeding and any additional milk that is needed, from donor milk or formula can be put in the supplementer bag. The other end of the tube, placed near the nipple goes in the baby’s mouth as they nurse. 

Your feelings are important. When IGT interferes with breastfeeding, talking with others that have had similar experiences and allowing yourself to grieve the loss of what your expectations were of a breastfeeding relationship with your baby. Work with a knowledgeable IBCLC who listens to you and helps you create a plan leading to a long and satisfying breastfeeding relationship between you and your baby.

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