When a baby is nursing, the mother making the breastmilk doesn’t really get a chance to inspect the milk that is nourishing her child, but when you’re a pumping mama it’s easy to become obsessed with the content of those little bottles.

For some moms, the amount of ounces in the bottles becomes a source of concern, while others take note of every color change. That’s why a breastfeeding expert in the UK, Nicky Gibbon of the Calderdale Breastfeeding Peer Support Service, recently posted a video using wine glasses and different colors of water

Using three wine glasses, a sponge, and different colored water, Gibbon explains why breastmilk looks different at different times. She uses blue water and cooking oil to represent milk and squeezes it out with a sponge, representing the different stages of feeding.


“When you first latch your baby on for a feed, that will start with rapid sucks and that is to initiate the letdown,” Gibbon explains, adding that during letdown your baby will be sucking and swallowing quite quickly as the milk is flowing fast.

As the wine glass slowly fills with blue water, she explains: “We would call this the thirst-quenching part of the milk. It has a high water content and is packed full of glucose to wake baby up.”

She continues her demonstration until she has a second glass of blue water with oil floating on top and a third glass that is mostly oil.

The video is controversial because while it is true that when a mother’s breastmilk supply is mature, the milk in the earlier part of a feed can be more watery and the later milk more dense and rich in fats. But lactation experts don’t want parents to be stressing about slight changes in breastmilk color or consistency.

As Nancy Mohrbacher, renowned International Lactation Consultant and author of Breastfeeding Made Simple writes, misunderstandings and misinformation about foremilk and hindmilk have created “anxiety, upset, and even led to breastfeeding problems and premature weaning” for some mothers.

Research has found this concept is not as simple as it sounds. It is true that fat sticks to the milk ducts in the breast and the percentage of fat in the milk increases during a breastfeeding as the fat is released from the ducts during milk ejections. But the reality of this seemingly simple dynamic is not always as it seems,” Mohrbacher explains.

“What’s most important to a baby’s weight gain and growth is the total volume of milk consumed every 24 hours,” she writes. “Let’s simplify breastfeeding for the mothers we help and once and for all cross foremilk and hindmilk off our ‘worry lists’.”

Her advice is especially important for pumping moms, who may notice that their breastmilk looks different at different times. That’s totally okay and does not mean that some of your breastmilk isn’t as good as other pumps proved to be.

This isn’t the first time an image has gone viral because mothers were worried about how their milk looked.

That was the case for a mother in the UK who posted a photo of two pump bottles last year and went viral. The bottle on the left shows milk that’s more of a cream color, while the bottle on the right is filled with milk that has a bit of a blue tint to it.

The mother who posted the photo to Facebook did not expect it to go viral, but it did. It spread in part due to her claim that the second bottle, pumped two days after her child received a round of vaccinations, is blue because her baby got those shots. It’s an interesting theory, but it’s not that simple.

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“It’s blue from all the antibodies my body is producing as it thinks she’s sick with what she was vaccinated against! When she feeds her saliva sends signals to my body to produce more milk with illness specific antibodies,” the mother wrote.

The idea that a baby’s saliva can trigger changes in breastmilk was popularized in 2015 and several mothers have posted viral images and claims similar to the above, but even scientists who study breastmilk say the idea that baby saliva changes breastmilk is still a hypothesis or a scientific work in progress. There’s a lot of good science backing this up, but it can’t be used to back up this claim.

As this photo has gone viral, doctors and midwives have suggested that the color difference in the photograph is more likely due to the mother’s diet or timing of her pump session than her child’s vaccinations. “It is well known that breast milk can change colour particularly with changes in mums diet,” Ian Currie, a consultant gynecologist at BMI The Chiltern Hospital in Buckinghamshire told Yahoo UK. Yahoo UK.

Just months before this photo went viral a study was published in the journal Breastfeeding Medicine which found that green breast milk can be caused by maternal ingestion of blue-green algae pills, a common supplement taken by many vegans and vegetarians. And sometimes breastmilk looks blue when it’s actually just thinner (as explained above), perhaps because it was pumped earlier in a session or at a different time of day.

The mom who posted this viral image disputes suggestions that her breastmilk’s color change could be attributed to anything other than the vaccinations, but there are no scientific studies linking vaccinations to changes in breastmilk composition. “My milk isn’t this colour from what I’ve eaten (not had anything artificially coloured/no supplements/no green vegetables), my milk is only ever this colour when my daughter has been sick…it’s never been like it when she’s be[en] well,” the mom wrote.

She may be certain that her child’s shots triggered the change in breastmilk, but there’s just not enough science to back that up and plenty of other reasons why this could have happened. It’s important for mothers who are seeing this viral image to know that.

There is still so much we don’t know about breastmilk and how it works, but we do know that as long as you’re feeding your baby (whether that’s breastmilk, formula or a combo of both) you’re doing a great job.

[A version of this post was originally published May 7, 2019. It has been updated.]