Choosing the Correct Breast Shield Size

By Kathy Moren RN IBCLC

I am seeing an increase in the number of women calling us and asking for a “fitting” of their pump breast shields. Many haven’t had their baby yet or are pumping but have no issues. But something they saw online made them think they needed to do this. Many resources detail how to measure your nipples for a correct fit, and many women want to make sure they get it right. 

Oddly enough, I have yet to be asked to do a “fitting” for a woman who is pumping but is in pain with obvious nipple damage. This often comes up naturally in conversation during a consultation. Many of these women already had a “fitting” and are using the shield they were told to, despite the pain.  Or they just assumed that pumping is supposed to hurt and are suffering needlessly. 

I want every woman to know that pumping should not hurt or cause damage. If it does, one of three things is happening: your nipple is not centered in the shield, your shield size is wrong, or you are increasing the suction too quickly. The first issue is easily fixed with instant relief noted. The other two take a little more effort. 

Several key indications that your shield size is wrong include pain, pinching, or nipple damage. This often includes bruising, blistering, or a wound similar to a rug burn or abrasion on the nipple, areola, or breast tissue. Another thing to look out for is the sound of breast tissue slapping against the shield or the areola and breast tissue being pulled into the tunnel of the shield. Pain, pinching, and blistering are caused by a nipple shield that is too small and rapid suction increase. The slapping sound and abrasions are caused by a shield that is too big. 

When pumping, you should always start on the lowest suction. If you are comfortable with that, increase it slowly. Go up by one increment, wait to see if you are comfortable, and increase again if possible. Eventually, you will reach a point that is not comfortable. When you do, dial it back to that comfortable level, wait a minute or so, then try to increase it again. You can increase to a higher level and pump comfortably if you do it this way. As the days pass, you can increase the suction much quicker than you were able to initially and still be comfortable. 

Rather than measuring your nipples and obtaining a fitting, I want women to pump based on how it feels and if they are getting milk. Immediately postpartum, the amount should be increasing as the days progress. If you can pump comfortably on a relatively high suction, get milk, and are done pumping in about 10 minutes, your shield size is fine. 

An important thing to remember about measuring is that some women have very elastic nipples that swell, immediately fill the tunnel when pumping, and rub on the sides, causing damage.  Others have nipples that don’t change at all. And still, others have nipples that elongate and actually stretch to touch the connector.  None of that is taken into consideration when measuring. It is critical to try another size if you have any discomfort or damage, provided you have determined the suction does not cause it.  

Here is a picture that shows what correct pumping with the appropriate size should look like:

Another thing to remember is that your breasts change considerably in the first weeks postpartum. Many of the breast pumps come with multiple sizes included, which helps with this issue. The shield you use on day 2 might differ from the one used on day 4 when you are engorged. And that might be different from the shield you use after 3 weeks, when your breasts often feel somewhat back to “normal.” By that time, you will feel fullness and the need to feed your baby before feeding but feel soft and comfortable afterward. Be open to using different sizes in that first month at different times. 

Please remember to trust your instincts and not settle for any pain, regardless of what the internet says or anyone tells you. When we see moms in the home, we often help them pump for the first time with their pump. We are happy to help you figure out what size works best for you if you need it.