Breast Pump Glossary and Breastfeeding Terms

2-phase expression

A feature on some breast pumps by Medela (Symphony, Pump In Style Advanced, not Original, and the Swing), that starts the cycling fast with less suction then after two minutes switches to slower cycling with more vacuum strength to imitate the sucking patterns of infants. A special let-down button can be pressed once to go instantly to the second mode. The manual breast pump Harmony is also said to have 2-phase. The first phase is initiated by squeezing the short part of the handle, with the longer, stronger strokes of the second phase coming from switching the hand around to squeeze the long part of the handle.


The dark circular area around the nipple. It is important during breast feeding for the baby to latch on with as much areola in his or her mouth as possible.

baby scale

For mothers concerned about low milk supply a baby scale is a tool to verify baby’s weight gain and also the amount of breast milk received in any given nursing. By weighing the baby before and after nursing and doing a little subtraction, one can determine the number of ounces the baby nursed from the breast. Since a nursing baby is usually more efficient than any breast pump, this method is preferred to breast pumping for determining how much milk the baby may be getting. For these purposes a baby scale accurate to 15 grams or less may be rented from many breast pump rental stations.

battery pack, batteries

In a breast pump, batteries give cordless convenience but vacuum strength and cycles per minute may be less than the user will find when using the AC adapter. Also pump cycling may slow as the batteries wear down. Slower cycles may cause some discomfort because the vacuum will be held longer on the breast. If this happens, reduce the vacuum and replace the batteries with fresh ones as soon as possible.

breast pump

A device that expresses milk from the breast. A misconception is that the breast pump suctions milk out of the breast. A breast pump’s job is to trigger the milk-ejection response or let-down. Most pumps achieve this goal by using suction to pull the nipple into the tunnel of the breast shield or flange then release, which counts as one cycle. Thirty to sixty cycles per minute can be expected with better quality electric breast pumps. It is important to note that in most cases the breast pump is not as efficient at removing milk from the breast as the nursing baby. Many mothers find their milk supply dwindling when they substitute too many pumpings for actual nursing sessions with their baby.

breast pump reviews

Opinions by actual users of the breast pumps. Two good places to find some reviews on the internet are Amazon and Epinions

breast shields, flanges, funnels

The part of the breast pump that actually touches the breast, covering the nipple and areola area. Medela breast shields fit almost all their pumps and come in sizes 21 mm, 23 mm, 27 mm, 30 mm, 36 mm, and 40 mm. Ameda uses different combinations of flanges and inserts to accommodate nipples in sizes 21 mm, 23 mm, 25 mm, 28.5 mm, 30.5 mm to fit all of their pumps but the Nurture III. See also SoftFit, Flexishield and Let-Down Massage Cushions.

closed system

Breast pumps designed for multiple users, such as hospital grade rental pumps. There is no possibility of breast milk entering the pump motor. See this article on used breast pumps for more information: Although the Avent Isis IQ breast pumps are said to be closed system, Avent still recommends their pumps to be single user.


The substance produced in the breasts during the final weeks of pregnancy. This “first milk” is highly concentrated in nutrition ideal for the newborn. It has been likened to an “antibodies cocktail.” Colostrum has a laxative effect on the baby, helping him pass his early stools, which aids in the excretion of excess bilirubin and helps prevent jaundice. With frequent nursings of 10 to 12 times a day, a mother’s regular breast milk will begin to appear or “come in” around day 3 or 4 after birth.


The suck and release pattern created by a breast pump to simulate what a nursing baby does.


cycles per minute. See cycling.

double pumping

Pumping both breasts simultaneously. Research with pre-term infants has shown double pumping can increase a mother’s milk supply, reduce expression time (yes, even cutting times in half) and produce higher levels of prolactin, the hormone that stimulates milk production after birth.


Any time an insufficient amount of milk has been removed from the lactating breast it may cause this painful condition. The engorgement that occurs when a mother’s milk first “comes in” is a little less understood, since swelling of the breast tissues themselves can be a contributing factor. There are many treatments, one of which is to use a breast pump briefly to soften the areola area so that the baby will be able to latch on easier.

funnel covers

The lid-like covers that snap over the funnel or breast shield of an Avent breast pump. The advantage of a cover is to keep the insides of the funnel and milk container clean and in ready-to-use condition.

Flexishield Areola Massager

A breast shield accessory that can be purchased separately and used with Ameda breast pumps. The Flexishield is designed to compress the areola area, helping to stimulate a let-down reflex. It is especially useful for smaller-breasted women who may benefit from the added stimulation.

hospital grade breast pumps

This group of pumps have a stronger vacuum strength than any other breast pumps and are the most suited to establishing and maintaining a milk supply in a mother who will not be breastfeeding her infant for long periods, as in the situation of a premature or sick infant.


Included with every Ameda breast pump except the Nurture III, a milk collection system that includes a special silicone diaphragm filter. This filter works two ways protecting the pump motor from getting contaminants in it and protecting the breast milk bottle from receiving contaminants from the motor. This extra amount of protection is desired for premature or sick infants or any mother desiring extra caution in the cleanliness of the collection of her milk. The use of the Hygienikit does not negate Ameda’s recommendation that all their pumps (except the hospital rental pumps) be single user, even though the Hygienikit IS the individual user kit for rental pumps.

lactation consultant

A highly specialized healthcare professional with advanced training in breastfeeding management. Because of the nature of their training, their advice on breastfeeding may be more specific and useful than what a mother will receive from her obstetrician or baby’s pediatrician.

lactation aid

A device that consists of a container of usually infant formula or banked breast milk and a long but narrow-diameter tube. The tube is inserted into an infant’s mouth along with the breast while nursing and provides extra nutrition to the infant while the breast simultaneously receives stimulation to encourage lactation. This also prevents a baby from becoming attached to artificial nipples while enabling a mother time to undertake strategies to shore up a lagging milk supply. Should be used under the advice of a lactation consultant as improper use could diminish milk supply.


Also known as the milk ejection response, it occurs when hormones cause muscles within the breast to squeeze and the ducts to widen, pushing the milk from all parts of the breast toward the nipple. Some mothers feel a tingling sensation; others feel nothing. Let-down is partly a conditioned response and can be encouraged while nursing or breast pumping by engaging in routines (i.e. sitting in the same place, drinking from a certain cup), looking at a picture of the baby, thinking of the milk flowing, or taking the mind off of everything about it.

Let-Down Massage Cushions

The Avent breast pump shields or flanges are soft silicone and have 5 petal-shaped bumps that move in and out to massage the areola and aid let-down. Available in only one size.

milk collection bags

Marketed under different trade names, these plastic bags are intended for the collection and storage of breast milk. They bear a resemblance to disposable bottle liners but have the notable difference of being thicker and stronger. For this reason milk collection bags are more suited for freezing breast milk and for using with breast pumps that permit attaching bags in place of bottles. Attaching disposable bottle liners to a breast pump will not permit a sufficient suction to be created for the pump to function properly.


Abbreviation for millimeters of mercury and as it relates to breast pumps it means strength of vacuum or suction. Sufficient pressure is needed to stimulate let-down, not to suction the milk from the breasts as is sometimes erroneously believed. Hospital grade breast pumps have the highest mmHg numbers and are the best for establishing a milk supply in mothers who need help in that area because of low supply issues or a hospitalized newborn. After a supply is well-established some users have found that “less is more” and adjusting the suction lower has enabled better let-down. Fortunately most electric pumps have adjustable vacuum strengths.

open system

A breast pump designed to be used by a single user. See also closed system, multiple user.

parts to assemble

As defined on the Breast Pump Comparison web pages, such as, all the breast pump parts that must be assembled or disassembled at each pumping session not including motor, AC adaptor or battery pack, milk containers, lids, stands, extra breast shields or inserts, totes.

parts to wash

As defined on the above referenced web pages, all the breast pump parts that come in contact with the breast or milk, and therefore must be washed every time the user pumps, not counting the receptacle(s) for the milk and the lid(s).

milk ejection response (MER)

see let-down.

multiple user

Hospital grade rental pumps are designed to be multiple user, and rental stations will require the non-refundable and non-returnable purchase of an individual accessory kit for the parts (shields, connectors, tubing) that actually comes in contact with the mother’s breast or milk.

piston-type manual breast pump

The pumping action is created with a sliding piston and cylinder and requires the use of two hands.

rental pumps

See multiple user

single breast pumping

Pumping only one breast at a time. Single pumping is useful for pumping one side while the baby nurses the other. For some mothers the ability to single pump enables them to soothe and hold their baby on one side while pumping the other.

single user

Most breast pumps are personal use items intended to be used by one mother only to prevent the transmission of diseases like HIV and hepatitis. See also closed, system, multiple user

SoftFit breast shield

The soft, flexible breast shield that massages the breast and areola when breast pumping, manufactured and trademarked by Medela. Can be used with all Medela pumps but the Little Hearts manual breast pump.


Awarded to breast pumps by actual users on Amazon and Epinions on a five-star scale with five meaning the best. Reading these reviews may be helpful because they often explain specific difficulties with certain breast pumps.

trigger-type manual breast pump

The pumping action is created with a squeeze handle similar to what one finds on a spray bottle. A one-handed breast pump.


Avent’s sturdy disposable container system for the collection and storage of breast milk. It can be used with all of Avent’s breast pumps and some other brands also. The disposable cup bases can be sterilized up to three times and are also suitable for freezing. Bottle nipples in a variety of flows are available to fit the system.


The warranty for breast pumps should be paid attention to and sales receipts saved. Pumps that get frequent use may wear out before their warranties expire.

Disclaimer: None of the content above should be construed as medical advice and all breastfeeding mothers should strive to educate themselves as much as possible from multiple sources and consult with doctors and lactation specialists as needed.

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