New study suggests pumped breast milk isn’t as beneficial to your baby as you think.

A new study published in Cell Host & Microbe found that breast milk from women who pumped tended to have more potentially bad bacteria than women who only breastfed.

The team of researchers looked at 400 samples, and while there was a wide variation of microbial balance at play, they noticed a common theme.

Milk from mums who pumped were higher in certain bacterial families (stenotrophomonas and pseudomonadaceae).

“To our knowledge, this is among the largest studies of human milk microbiota performed to date,” said senior study author Meghan Azad, a researcher at the Children’s Hospital Research Institute of Manitoba and a Canada research chair in developmental origins of chronic disease at the University of Manitoba.

“Contrary or in addition to the hypothesis that milk bacteria come from the mother’s gut, our results suggest that the infant’s oral bacteria are important in shaping the milk microbiota,” Azad continued.

“Our results suggest that both the act of pumping and the lack of contact with the infant oral cavity may independently influence the milk microbiota, although we cannot definitively distinguish between these related factors, nor identify the sources of the exogenously derived bacteria in the expressed breast milk.

“Nevertheless, based on lower richness associated with indirect versus direct breastfeeding in both manually expressed and pumped milk samples, we speculate that exposure to the infant oral cavity has a persistent impact on shaping the milk microbiota community.

“Further research is needed to characterize this “retrograde inoculation” process, and to explore the possible impact of pumping on the microbiota of expressed milk.”

You can find the full study here

 Share your comments below

  • As the last line reads, ”further research is needed…”


  • Interesting – but not everyone can choose what their body will do around feeding.


  • Although the pressure to breastfeed is high, this article is interesting. It makes me contemplate why I’m trying to pump so much.


  • If it prompts more mothers to breast feed instead of pumping then good, because it is better for baby and mum too, and of course pumping is better than formula.


  • Really? It sounded like the study released findings then wasn’t sure and the findings needed more research. Not everyone can breastfeed, and not everyone who breastfeeds can do skin-to-skin contact all the time. Let’s stop putting pressure on feeding our babies and know that Mums will always do what’s best for them.


  • Well unfortunately some women don’t have the luxury of always being able to be there. Studies aside a) it’s better than formula and b) it doesn’t seem to hurt.


  • So when the baby drinks the milk that has been expressed his oral cavity will once again shape the milks microbiota.


  • I could only pump for my first born, she wouldn’t latch on and I didn’t want to purely formula feed so I extracted as much as I could. I wonder if it also comes down to how you deal with it afterwards and how it is stored with regards to these bacteria?


  • I do think that breastmilk is adjusted to your baby’s needs indeed. For some mums pumped breastmilk is the only way. Still think it’s better the formula. And where does this leave donor milk ?


  • With each new study I am glad my BF days are behind me. It is getting harder and scarier to look after babies with each new study that comes out.


  • Breastmilk that is expressed can be frozen for a limited amount of time. In a dire emergency if used within the time limit it is better than trying to get a baby to take formula instead of slow introduction.


  • So they didn’t see the woman who has on boob for her newborn and one for her toddler and the difference in her milk for each child

    • That actually supports this article. They’re saying that the baby/child’s oral bacteria affects the milk. Thus the milk being different from each breast with different children


  • Interesting. It’s true that the babies oral bacteria affects breastmilk. I read that if a baby is getting sick their oral bacteria signals the mothers breastmilk to contain more antibodies to help protect them against it.

    • That’s very interesting and amazing that our bodies can do this for a child


  • This is just another ploy to put down mother’s that find it hard to breastfeed but want to still do what they can for Thier baby.
    Enough with these silly studies. All mums out there, do what you think is best when breast, express or bottle feeding.


  • Are you kidding me?! At least the babies are getting breast milk. Some mums have no choice but to pump. Surely the extra bacteria will be good in building their immune system?? As if mums aren’t slammed enough :(


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