If you have pumped breast milk for any length of time, you are probably very familiar with the intricacies and nuances of a breast pump and its parts. You need to know what parts go where, what suction levels work best for you, and how long you should pump. It’s not an easy undertaking, but with practice it becomes second nature. Some moms, however, experience difficulties with pumping breast milk, particularly when it comes to milk production. If you fall into this group of moms you may be wondering does flange size affect milk output? The answer is yes.
How to Know What Size Flange to Use
First, let’s define what a breast flange is and why it’s essential for pumping breast milk. A breast flange, also known as a breast shield, is a funnel-shaped device that fits over the nipple and areola. It attaches to the breast pump via tubing and creates a vacuum that stimulates milk letdown and draws out breast milk. Breast flanges come in different sizes, typically ranging from 21 mm to 36 mm in diameter. We have a helpful guide to Determining Your Correct Flange Size (So Pumping Doesn’t Hurt) that covers how to determine your breast pump flange size.
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Does Flange Size Affect Milk Output?
Breast flange size can affect breast milk output because it determines how much breast tissue is being stimulated during pumping. Incorrectly sized pump flanges can affect milk output in a number of ways. These include compression of milk ducts, improper seal around the nipple, and inefficient removal of milk from the breast. The key to pumping breast milk is to ensure that the correct amount of breast tissue is being pulled into the flange. Here is what your nipple should look like in a flange:

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What Happens if Flanges are too Small?
If the breast flange is too small, it may not fully encircle the areola, resulting in poor milk flow and reduced milk production. Your nipple isn’t being stimulated correctly and could end up damaged. It’s similar to if your baby has a bad latch. This ineffective removal of milk due to the flange can affect milk output and lead to less production over time. Additionally, when a flange is too small it can cause compression of the milk ducts, resulting in clogged milk ducts, tears in your nipple, and less milk being removed from the breast. All of these factors can cause discomfort, pain, and inadequate milk removal when pumping.
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What Happens if Flanges are too Big?
Conversely, if the breast flange is too large, it may not create a proper seal around the nipple. This can result in air leaks (and accompanying loud farting sounds–yes, really) and reduced suction. If your pump flange is too big, it can also cause pain by pulling too much of your breast into the flange. Too much breast and not enough suction due to a large flange size affects milk output by reducing the amount of pumped milk. This is the same scenario we outlined above if your pump flange is too small.
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How to Know What Size Flange to Use?
To determine the correct breast flange size, moms should consider several factors, including nipple size, breast size, and pumping comfort. Nipple size is particularly important because it affects how much of the areola is drawn into the breast flange during pumping.
If you have larger nipples, you may need a larger breast flange to ensure proper stimulation and milk removal. On the other hand, if you have smaller nipples, you may need a smaller breast flange to avoid discomfort and reduce the risk of nipple trauma. If you have no idea if your nipples are considered small or large, check out our guide on Determining Your Correct Flange Size. We have pictures, tips, and links to all sizes of flanges there.
Breast size is also a crucial consideration when selecting a breast flange size. Women with larger breasts may require larger breast flanges to accommodate more breast tissue. While women with smaller breasts may benefit from smaller breast flanges. However, breast size alone does not necessarily determine the correct breast flange size. It’s essential to consider other factors, such as nipple size and overall pumping comfort.
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Breast flange size can affect breast milk output and ultimately impact breast pumping success. Selecting the correct breast flange size based on nipple size, breast size, and pumping comfort can help ensure proper stimulation, milk removal, and overall comfort. Pumping should never hurt or feel uncomfortable. If it does, something is wrong. Troubleshoot using the above information and don’t hesitate to try a couple of different pump flange sizes. Your breasts will thank you when you find the right fit.