The In and Out of Breastshield Sizing…

Once upon a time you were blissfully unaware of the existence of breastshields.  And then you became a mom and for one reason or another you found yourself in relationship with a breastpump and everything changed.  You did what you could to sincerely embrace this new baby in your life.  You downloaded the PDF manual, saddled up to the motor and held the breastshields up to your bod and thought, “What have I gotten myself into?!”  The things we do for our babies!  And after a little while you may have looked down and stopped to ponder…the breastshields.

Breastshields, aka flanges or, the more archaic horns, are integral components of a breastpump and proper fit is essential for both a mother’s comfort and effective drainage.  Chances are you didn’t get a merit badge in Girl Scouts for fitting these devices.  Chances are pretty good that you never even touched one until you cracked the safety seal on the carton of your breastpump. You may have assumed that the flanges that came with the pump were the only ones available and just went with it.  Or, more  than one size might have been included with your pump and maybe you’ve been scratching your head in prolactin-induced wonder about which ones to use.  Is bigger better?  Or maybe, just maybe, you experienced pumping to be uncomfortable with either set and assumed you were doing something wrong.  Or, dare I suggest, you may have even thought that shield size is dependent upon breast size.

Enough with the rhetorical questions already!  We’re here to set you straight ladies, and give you the real deal, the ins and outs, about the proper fitting of breastshields. You want and deserve a comfortable fit.   It’s an inexact science and it has nothing to do with the size of your breasts…it’s all about the size of your nipples!  Who knew?  And that’s exactly why there is an art to achieving a proper fit, so let’s talk nipples, shall we?

Breaking news! Not all nipples are the same and they may even change size after delivering your baby! Gasp!  We all knew we had to keep track of hem lines, but now this too?  To further complicate matters, your left nipple and right nipple may be of different sizes as well.  Studies have been conducted to measure nipple sizes of lactating women and found that most women’s nipples fall in the range of 12 -23 mm at the base of the nipple.  A fact that won’t make it to Tuesday Trivia Night at the local pub…Just as feet and hands and noses come in all different sizes, so do nipples.  Viva le difference!  Happily, just as you wouldn’t settle for a pair of ill-fitting shoes, you don’t have to settle for an ill-fitting shield either.  While you’ve probably known how to get a decent fit with shoes since your Buster Brown days, how to achieve a good fit with a breastshield may be a thing of mystery to you.

Measuring a foot to fit a shoe is pretty straight-forward, since your foot doesn’t change size when you’re walking around. You measure length and width and get a standardized size.  And while breastshields come in standard and non-standard sizes, measuring a nipple can be a tricky endeavor.  A nipple at rest is not the same size as one at work.  Put a nipple in a breastpump and just watch it grow.  LCs in the field have observed and reported nipples to increase in size by 3-4mm during pumping. With all these size variations and fluctuations, how does one begin to determine the proper fit?  And, does it all really matter?

You may have sacrificed comfort for style when it comes to your shoes, maybe even tolerating a blister now and again in the name of fashion.  Isn’t a little discomfort to be expected when saddling up to a pump?  The answer ladies, is a resounding “NO!”  The potential clinical implications of all this variation in nipple size and flange fit is no joking matter.  Continued use of a too-small shield can abrade the nipple (Ouch!) and even lead to secondary infection.   Furthermore, a too tight flange can interfere with proper drainage.  The number of ducts in the nipple ranges from 19-28.  These tubes are the pathways that milk must travel through to reach the nipple pores (did you know you’ve got 10-14 of those?) before exiting the body.  Constriction of these tubes limits flow and drainage.  With prolonged use and prolonged mother-baby separation (how do you say, ”back to at work 12 weeks postpartum?”) the long-term implication is diminished supply and increased risk for plugged ducts and the need for supplementation. For mothers pumping in the early stages of lactation, suboptimal drainage can set the stage for insufficient milk supply. Yikes!

A too-large flange isn’t necessarily any better.  When a shield is too big for a nipple, excess breast tissue is sucked into and compressed by the walls of the shield.  The ducts are pinched and this strangulation effect causes flow and drainage to be suboptimal.  All of these effects potentiate shorter breastfeeding duration and less milk getting to baby.  The long term health implications for baby and society are real.  In other words, flange fit really matters!
The point of all this isn’t to terrify you or frighten you away from pumping.  The point is to inform and empower.  The good news is that just as women and nipples come in all shapes and sizes, so do breastshields!  Pump manufacturers are wise to this and have multiple sizes available.  Be warned, they all have proprietary sizing, so one brand’s standard size is not the same as another and they are not interchangeable.

For example, Medela provides their “standard” size (24mm) and a larger breastshield (27 mm) in the kit of all of their retail breastpumps.  Additionally, they offer 21 mm, 30 mm, 36mm, and 40 mm sizes.  We stock the 24, 27, 30 and 36 mm flanges and can special order the 21s and 40s.  Hygeia, another well-known breastpump manufacturer has made their “standard” size (27mm) provided with the pump larger than the “standard” size provided by other companies.  They also offer 29 mm and 31 mm. Apparently ladies, just like hem lines, nipple sizes are going up too!

But with all these options, many new moms are confused as to which is the right size for them.  Which begs the questions:  How do you know if you’ve got a proper fit?  What does a proper fit look and feel like?   Well, under ideal conditions, the breastshield fits over your nipple and forms a seal around your areola.  The pumping action mimics the nipple stimulation of a baby nursing.  Vacuum is created by the pump and the nipple is gently pulled into the shield tunnel.  A good fit allows the nipple to move freely and comfortably within the shaft of shield, minimizing friction points.  The areola is gently compressed, allowing for rhythmic expression of milk.

The pumping mother is the ultimate arbiter of proper fit.  Comfort rules the day.  Our recommendation is to use the smallest size that allows for comfortable pumping at your pump’s maximum pressure setting.  It’s important to be able to pump at the maximum pressure setting in order to optimize drainage and stimulation. If you have fairly average-sized nipples, start with the standard, give it a try and if you are not comfortable try the next size up.  You can also use lubrication around the shaft of the shield for increased comfort.  Purified lanolin, your own milk, or extra-virgin olive oil would all be great options for lubricants. Be aware that you may need a different size shield on each breast to accommodate for asymmetry.  Your nipples will swell with pumping, so if you’re comfortable at the beginning of the pumping session and sore at the end, you may wish to size up.  If you start with a standard flange and notice your areola being drawn into the shaft of the pump, you probably need a size smaller.  Remember, the goal is comfort and drainage.  If you are struggling to achieve both, consider reaching out to an LC.  She may need to observe you pumping in order to best evaluate the fit.  We offer phone support with all of the pumps we sell, either retail or insurance, so you don’t have to settle for uncomfortable breastshields.  Now, as for those hemlines, you’ll have to keep track of those for yourself!

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  • Thank you for this article. It was very helpful. When I measure my nipples, is it circumference or diameter that I measure to get the proper size. I’m thinking of getting an Ameda pump but additional sizes flanges can only be ordered online around here so I would like to order in advance if I have to.

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