Flange Size Matters! | CAPPA

jeanette april 2024 newsletter

Jeanette Mesite Frem MHS, IBCLC, CCE is an internationally recognized speaker on pumping, feeding gear, and especially, updated flange fittings. He is the co-investigator for a soon-to-be-released research study, the first to look at flange sizing. It compares “standard” flange fitting recommendations to Jeanette’s Flange FITS™ Method, which uses a different method of measuring and assessing flange fit. At her private practice, Babies in Common in Northborough, Mass., Jeanette teaches prenatal breastfeeding and birth preparation classes and provides support to families with breastfeeding/breast, lactation, pumping, and feeding concerns. in the bottle. We talked about how her flange-fitting method, which she teaches perinatal professionals, has improved pumping for so many lactating parents.


Julie Brill, IBCLC, CCCE, CLD: I’m so glad we were able to chat about proper flange size, because lowering has been a game changer for so many clients in my clinical practice. Pumping parents at work and exclusive pumpers are thankful to get more milk in less time. But I think the most affected are those who pump to increase milk production; we find that the right measure often gives them the help they need to continue. We’ve come a long way since my kids were babies in the 1990s and only had a 24mm flange!

How did you start raising parents smaller? This is really thinking outside the box, when the general thought goes up if pumping is uncomfortable or the nipple swells while pumping. I remember about seven years ago when you gave me those youth-sized flanges. I thought they fit a doll! What gave you the confidence to encourage parents to try them?

Jeannette: Thanks for asking me about this topic—it’s a passion project for me. Like you, I have found it to transform the pumping experience for so many. It’s also very rewarding for the perinatal professionals who do it with their clients. I, too, was pumping in the early 2000s with standard size flanges; I don’t work full-time, but I still have to pump several times a week in addition to when I’m at work, to provide enough bottles when I’m at work. And pumping is uncomfortable.

Eventually I owned a maternity and parenting center where we rented pumps and sold flanges. We have a client with a low milk supply who comes to our breastfeeding groups. He shares that he gets more milk with a smaller flange: a 21mm. (Medela did this and then stopped for years.) Others have found the same results. Eventually, when I started working as an IBCLC, more and more smaller flanges started to come on the market and I heard they were working for some; so I learned from clients and colleagues. And I tried new things and found more success!

Julie: What do you see for an average flange size? How often do parents need different sizes for each breast? And why do you think pump companies still make oversized flanges?

Jeannette: Based on my practice and what many, many lactation professionals around the world have reported, the most common size is 13-16. If a parent tells me their size is a 19 or larger, I wonder if that’s true. I know this is true for some, but most people are 17 and under. Yes, pumpers often require a different flange size for each side, and that size can change over time. So, try smaller sizes (1mm by 1mm at a time) if pumping becomes uncomfortable or they want to see if they can produce more milk.

Why do pump companies make oversized flanges? This is the usual answer: “that’s what we always do.” No one was asking this until recently. And I guess they’re wondering how they’re going to recycle all the flanges they’ve already made AND how they’re going to put the new flanges in the boxes if they change what they’re doing. I have given feedback to most pump companies about this but so far few seem to really care.

Julie: Lactation is a field where our knowledge base is changing rapidly and yet we continue to see resistance to change and even new research. What kind of reception have you received in the breastfeeding community?

Jeannette: Many milking professionals are interested and excited to see how different flanges work. Some resist, and ask “where is the evidence for using smaller flanges?” The sad but true thing is that there is no evidence for the use of standard size flanges, or the reason WHY standard sizes are standard sizes! There are still too many lactation/perinatal professionals who think they should measure the base of the nipple and add a certain number of mm to the flange size. Flange fitting is like shoe fitting: we can measure, but you have to walk in the shoe a bit to decide if it fits. The human body is not standard.

Julie: Can you share with us about the research you are doing on flange size?

Jeannette: There has been no prior research comparing standard sizes to smaller sizes. But it’s not just about a smaller flange. Sometimes smaller flanges hurt more, so our instinct is NOT to go smaller, for fear of hurting more. But flanges that are too small don’t hurt, they just don’t produce milk and a nipple doesn’t move on them. We want to see the nipple sliding down the sides of the tunnel AND amazing comfort AND milk spraying most of the time. Fortunately, a great research professor, Lisa Anderson, PhD, RN, IBCLC of the University of North Carolina Greensboro, reached out in 2022. Together we will release the results of the first flange study fitting! We are now in the writing-it-up, hoping to have it published this summer.

Julie: In my practice, I’ve seen parents with properly sized flanges comfortably increase the vacuum on their pumps and get more milk in less time. Many say they don’t bother with hands-on pumping techniques anymore, or that they don’t need much. Do you think massage and compression are still necessary when the flanges are correct?

Jeannette: I also find that hands-on pumping isn’t always necessary. I would recommend breast gymnastics/the milkshake before pumping, mid-pump, and to the end. It gets the milk flowing, it gets the oxytocin flowing, and it’s especially helpful when the milk flow stops. That’s great for many. Does everyone need it? Nope. Do some people still need massage and compression with pumping? Yes, because there are cases where the flange fitting is more complicated. Some people need larger flanges because of their breast anatomy (we can’t see what’s under the skin—we have to TRY different flanges to see what results best for comfort, -milk spray, and pumping efficiency).

Julie: Can flange fitting be done virtually?

Jeannette: Yes, but the gold standard is for people to measure their nipple TIPS (it’s NOT the base that matters) after they’ve stimulated the nipple well. First we need to know the diameter of the tips. Then I recommend they buy flanges that size and 1mm smaller and one or two slightly larger. We need them to TEST those flanges in a pumping session, while we work closely with them, to assess comfort and spray.

Julie: How can doulas and CLEs learn more about your parenting techniques?

Jeannette: I offer a course for perinatal professionals, which includes doulas, CLEs, and anyone who works with parents who pump. The course also covers bottle feeding and other feeding equipment, such as nipple shields. This includes 5.5 CERP and CAPPA CEUs. While there are aspects of lactation support that are within the purview of IBCLCs, I think that knowing updated techniques and information about pumping and flange fittings and bottle feeding are things that everyone should be aware of. anyone working with perinatal families. More information about my course can be found on my website:

Julie: Finally, what would you say to people who are concerned about the cost involved in testing different flanges?

Jeannette: Honestly, the formula is expensive. Breast milk is not free, we know it takes time. But we’re trying to help babies get more human milk and help people reach their milk production goals. That can be expensive. Fortunately, flanges are not always very expensive.

I would prefer that all perinatal professionals have flange fitting kits so they can do a personal flange fitting. Then people just have to buy the ones that work best. I want to eventually be a resource for low-income families in every community where flanges are provided, with guidance on making sure they are sanitized appropriately between people. It is not impossible; it just takes a few people to help make changes in their community. Because flange size matters and flange fitting can change pumping for parents and babies!


Julie Brill, IBCLC, CCCE, CLD, Faculty

Julie Brill has been training CAPPA labor doulas and childbirth educators for over 20 years. She has a busy private practice helping parents feed their babies virtually and in person in Massachusetts. She also offers private, independent, virtual lactation and childbirth classes to expectant families and CAPPA virtual trainings for doulas and childbirth educators. Her virtual course Breastfeeding for Birth Professionals earns 3 CAPPA CEUs. Julie is the author of the doula anthology Round the Circle: Doulas Share Their Experiences and the mother of two grown children. Reach him at

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