Milk and Breastfeeding – The Workings Of

Originally published July 17, 2018

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Milk sustained us as we grew from tiny bubs to wee toddlers, right through to the energetic kids darting roaming the streets. Whilst humans often drink milk their entire lives, it is a vital part of infancy and motherhood in every mammal that has walked this earth. So why is it that few people understand how milk is produced, and what is going on in a female’s body leading up to breast feeding?

Colostrum, the first dose of milk that is rich with antibodies, is another matter entirely. But for the most part, breast milk in most mammals is produced the same way, whether you’re a human, cow and cat.

The nipple is filled with nerve cells, and as a baby suckles, those nerve endings are stimulated (switched on). The pituitary gland, a pea-sized organ at the base of the brain, then picks up the signals from these turned on nerves. The signals tell the pituitary to release the hormones prolactin and oxytocin, two very important hormones.

Both these hormones are responsible for a variety of things, but during milk let down (the process of breast feeding), they have some key functions. Prolactin causes your alveoli (a part of your breast surrounding your nipple) to use the nutrients in your blood and transform them into breast milk (quite bizarre that your blood can become milk, really). Oxytocin then triggers the cells around the alveoli to contract, forcing milk down the milk ducts.

This is the let down reflex.

For those humans out there, the expectant mother-to-bes, there are three ‘types’ of milk to be aware of. There’s the colostrum, which has been made in your breasts since around week 28, and may have been leaking a little since then as well. This is a highly important milk, designed to give a baby the best start to life. Colostrum is rich in antibodies, known specifically as secretory immunoglobulin A. As colostrum turns into normal breast milk, these antibodies decrease in concentration, though the volume of milk increases (increasing with the size of your babies tummy).

The other types of milk are foremilk and hindmilk. Their names suggest what they are. Foremilk comes first during suckling, and is the first milk the baby receives during a nursing session. It is watery and thin, quenching baby’s thirst, and has a slight blue tinge. After several minutes of nursing, the milk becomes less watery and grows thicker, similar in texture to cream. This milk, hindmilk, is high in fat and has a relaxing effect on baby. This milk makes your baby feel full and encourages weight gain (a good thing!).

Make sure you feed your baby until you see that sleepy, happy, content look cross their face. That’s when you know they’ve had a bit of the hindmilk as well as the foremilk, and can finally be put down to rest (since we all know that you’ll be the one needing most the rest between feedings, especially in the first few weeks when they seem to never end).

Feel free to ask more questions about milk and breast feeding. Though all this knowledge comes from learning about animal husbandry, we are all mammals with very similar internal bodies, even if our outsides look vastly different. I would have aimed this article more at the cows I was thinking of when writing it, but seeing as they can’t read, I thought I’d aim it more at those humans that are expecting instead.