There is a research project which should be publishing results soon. 

But more importantly- where did the size 24 come from?  Where  is the research? 

As I understand it, a man in the 1800s developed a pump and made the piece 24 mm. When the first big electric pumps were developed, from what I understand the pump develops (Ameda etc) stayed with that number. Was it baby mouth circumference. I have no idea where 24 came from? 
Now that we have so many women pumping with electric pumps, some exclusively, with all sorts of results, pain, damage to nipples etc. i applaud those who thought outside the box, and not just bigger!  
I was skeptical  at first, but now that I’m fitting people, letting them try 3-6 sizes or more. I really see the value in this option. I look forward to the research, but there should never be one size fits all, with no research prior to this attitude,  just look at how different breasts are in size, firmness, shape and everything else. 
Janet Dombro, IBCLC 

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