Choosing a Properly Fitting Breast Shield

If you are using a breastpump to remove (express) milk for your baby, it is very important that you have correctly-fitted breastshields. The breast shield is the part of the pump collection kit that fits directly over your nipple and forms a seal around the areola (the darkened part of your breast). The breast pump works by creating a vacuum, which gently draws your nipple into the tunnel of the breast shield--just like your baby would draw it into the mouth with sucking. A correctly-fitted breast shield will help make your pumping comfortable, and allow the pump to remove as much of your milk as possible with each milk expression.

Some mothers do well with a standard breast shield, but many mothers appear to benefit from a smaller or larger shield. How do you know if you're one of them? The part of the shield that affects fit is the width of the opening. This is called the nipple tunnel. As you pump, your nipple is pulled into the nipple tunnel.

One way to know you need a larger shield is if pumping hurts, even on low suction. But there are other ways to tell. You can, for example, measure your nipple. If your nipple at rest is as wide as a US nickel (22 mm) or larger, you likely need a larger size. But even if your nipple is smaller than a nickel, you might still need a different breast shield size because the breast changes as you pump.

The best way to gauge size is while pumping. It is almost impossible to tell which size breast shield is the best fit without watching the nipple movement during pumping. The following tips will help you determine whether a different size breast shield would be right for you. Then, you can discuss your observations with your nurse or lactation specialist.

To determine whether you think you might need a Large or Extra Large breast shield, look at your nipple as it is drawn into the tunnel of the shield during pumping. It should move freely and easily, and should not rub against the sides of the tunnel. You know you have a good breast shield fit when you can see some space around your nipple as it is pulled into the nipple tunnel.

If your nipple always rubs along the flange sides, it is too tight. If the breast shield fits tightly, your nipple will rub against the sides of the tunnel with each vacuum movement of the pump. After several pumpings, you may notice that the outside of the nipple (rather than the nipple tip) is tender or sore. You may also see a little ring of skin flecks in the tunnel of the breast shield after you pump. While a little circle of milk in the tunnel is normal, a ring of skin flecks probably indicates that the tunnel is too small, and that you would be more comfortable with a larger breast shield. When your nipple moves freely in the tunnel of the breast shield, you will also note a gentle pulling movement in the areola each time the pump cycles. If you do not see any movement in the areola with the pump vacuum, the breast shield is probably too small. Rubbing may cause pain, and friction can even break the skin.

A tight fit squeezes the milk ducts and slows milk flow, which can lead to problems with your milk supply. During pumping, your milk flows out of the breast due to a combination of the pump's vacuum and your milk ejection (or let-down) reflex. However, a tightly-fitting breast shield does not allow good breast emptying--even with the best breast pump and a strong milk ejection reflex--because it squeezes the small ducts inside the nipple that carry your milk out of the breast. Ordinarily, these ducts increase in size when you feel milk ejection so that the milk can flow out of the breasts quickly and easily. However, if the ducts are squeezed by a tightly-fitting breast shield, some milk stays behind in the breast. Eventually, this incomplete milk removal can lead to plugged ducts, mastitis, and problems with low milk volume. You may note breast engorgement that seems to last a long time--or little "knots" or hardened areas in the breast that do not seem to empty with milk expression.

If you have either or both of these symptoms--nipple tenderness around the outside surface of the nipple or problems with breast emptying-- your pumping will probably be improved with a larger size breastshield. You will want to correct this problem as soon as possible after your baby's birth before the nipple tenderness and back up of milk in the breasts affect your milk supply. If your kit contains larger flanges, replace your standard flange with a larger flange. Try the flanges until you find a size that feels best and pumps the most milk.


This is general information and does not replace the advice of your physician or healthcare provider. If you have a problem you cannot solve quickly, seek help right away. Every baby is different, and your baby may not be average. If in doubt, contact your physician or other healthcare provider.

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