From green to blue, yellow and red: Here's what the colour of your breastmilk means.

Mother of a newborn, Monique, called me in a state of anxiety. She said, “I think I am going to have to wean, I expressed some milk this morning and it’s green. What the hell is happening? I can’t feed my baby this!”

The thing is, if your baby is feeding directly from the breast, you probably wouldn’t notice what colour your breast milk is. As long as your baby is happily feeding, it’s unlikely there is a problem or that your baby is at any risk, regardless of the colour of your milk.

Your breast milk is perfectly suited to your baby’s stages of development and it changes composition – and colour – over your breastfeeding journey and even throughout an individual feed. At first, during late pregnancy and immediately after birth, your breasts will produce colostrum, a sticky, yellow or orange tinged liquid. High levels of beta-carotene give your colostrum this yellow colour.

Over the next few days, as your hormones and baby’s suckling stimulate your milk to ‘come in’, this ‘transitional’ milk can look creamy and yellowish gradually changing to white. Over the next week or two your breasts will produce ‘mature’ milk. Mature milk can change colour from a watery ‘bluish white’ to a more ‘creamy’ white colour, depending on the fat content of your milk.

The fat content of your milk increases over the course of each breastfeed as the higher fat milk (hind milk) is released by your letdown reflex as this is stimulated by your baby’s sucking.

What makes my milk change colour?

One of the factors influencing the colour of your milk could be the foods you are eating. For instance, your milk may look pinkish if you have been eating beetroot; orange if you have had pumpkin soup or green if you have been guzzling green smoothies loaded with spinach. Some medications, herbs and vitamins can also alter the colour of your breastmilk.

After a chat with Monique, it turned out she had been taking a multivitamin. When she stopped the multi vitamin, she no longer had greenish coloured milk. And because the vitamins were safe to take while breastfeeding, Monique was able to continue taking her vitamins without worrying that her milk would harm her baby.

What if my milk is bluish and watery?

Some mothers worry that the ‘bluish’ and ‘watery’ milk is not ‘good quality’. This myth is often perpetuated by older women who used to be told this by health professionals. A generation ago, many women were advised to wean their babies because their milk was ‘poor quality’ or ‘not strong enough’ if their baby wasn’t gaining ‘enough’ weight. Sadly, the issues with infant weight gains were more likely due to rigid feeding regimes that were popular at the time and comparisons to baby weight charts that were based on formula fed babies.

Fortunately, we now know that rigid feeding regimes are not compatible with breastfeeding: women have different breast milk storage capacities so may need to feed more frequently to maintain a healthy milk supply. Babies who are allowed to regulate their own feeding patterns will also determine the composition of milk that they need. For instance, on hot days babies will have more frequent short feeds of lower fat milk to quench their thirst. If they are hungry, they will suck for longer and get more higher fat hind milk.

Thankfully, the WHO child growth charts are used in most areas. These are based on breastfeeding as the normal for infant growth patterns. So, as long as your baby is following a curve on these charts, is healthy and happy, you can relax. If you are worried, check with a health care professional.

On this episode of our podcast for new parents, we talk nutrition, raising a toddler who’ll eat everything, and when it’s time to transition to solids.

What if my milk is rusty or reddish brown?

If your milk looks rusty/reddish brown, this can indicate blood in your milk. Reassuringly, this is unlikely to be anything sinister (such as breast cancer), but it’s always important to get this ruled out if it continues for more than a few days.

Blood in your milk is most likely due to bleeding from a cracked or damaged nipple. Also, according to an Australian Breastfeeding Association article, it is common to have blood stained colostrum or milk in the first days after giving birth. This is thought to be as a result of the growth of the ducts and milk-making cells in the breast and does not persist beyond about seven days.

A less common condition that may cause blood in breastmilk is an intraductal papilloma — a small benign wart-like growth on the lining of a milk duct, which bleeds as it erodes. The good news is that if there is a wee bit of blood in your milk (from a cracked nipple, perhaps) it won’t harm your baby and you can continue to breastfeed.

The important thing to remember is if your baby is happily breastfeeding, you don’t need to worry about the colour of your breastmilk – it’s the perfect food for your baby, whatever colour it is. Of course though, if there seems to be something wrong with either your breasts or your baby it’s always sensible to get checked by a health care professional.

A version of this post originally appeared on PinkyMcKay.com and has been republished here with full permission.

Pinky McKay is Australia’s most recognised and respected breastfeeding expert and gentle parenting advocate. She’s an Internationally Certified Lactation Consultant (IBCLC), mum of five and best-selling baby-care author. Pinky is also the creator of Boobie Bikkies, all natural and organic cookies to support a healthy breast milk supply.