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Collecting and Storing Breastmilk
by Anne Smith, IBCLC

There are many situations in which a mother may need to pump milk from her breasts. Some are short term--for example, occasional separations, mother on medication incompatible with breastfeeding, breast engorgement, severe nipple soreness, or increasing milk supply. Some are long term--a premature hospitalized infant, or regular separations such as those encountered with returning to work or school. Whatever your reasons for expressing your milk, certain tools and techniques can help you be successful in obtaining the milk you need and maintaining your milk supply.

First, you need to decide if you need a pump, and if so, choose one that meets your individual needs. For occasional short- term separations (such as a weekly evening out) a manual pump or hand expression may be adequate.

I think every nursing mother should learn the technique of hand expression, because it can come in handy on so many occasions. You may need to soften your areola (the dark area around the nipple) before the baby nurses to make it easier for him to latch on, you may want to express a little milk in the shower if your breasts are uncomfortably full or you have a plugged duct, or you many want to express a little milk directly into your baby's cereal bowl once he starts solids. There are many occasions when you just want to get out a little milk but not empty the whole breast, and at these times you may not need to use a pump at all.

This is the basic technique for hand expression:

  • Wash your hands before you start.

  • Express into any clean container - bottle, cup, bowl, etc. You don't need to boil it, just wash with hot soapy water or run it through the dishwasher. Don't touch the inner surface after you clean it.

  • The key to any kind of milk expression is to get the milk to 'let-down'. Electric pumps stimulate the let-down reflex automatically by mimicking the baby's sucking action, but when you are hand expressing or using a manual pump, you may need to stimulate the let-down reflex yourself. Some women's milk lets down easily, but many mothers have to work at it. To help your milk let down, try: looking at a picture of your baby, smelling and holding a blanket or piece of clothing that smells like him, massaging the breasts, gently rolling the nipple between your fingers, taking a hot bath or shower before expressing (or try expressing while you are in the tub), apply warm compresses to the breast, look at your baby's picture, or drink a glass of water or juice before starting to express. Anything that helps you relax will help your milk let-down - this can include settling into a comfortable spot, listening to music, taking deep breaths, having your partner rub your shoulders, etc. Some mothers report that the first few times they pump, they are nervous and don't get much of a let down, but after they get into the routine, they find that their milk is leaking out as soon as they look at their baby's picture or hear the sound of the pump motor if they are using an electric pump.

  • Hold the breast with one or both hands depending on the size, with the thumb on top and the fingers underneath. Gently compress the tissue between the fingers and thumbs while rolling them forward, rotating around the breast. Or, use the tips of your fingers to massage in small circles all around the breast, similar to a breast exam. You can also do this type of massage during pumping to encourage the flow of milk.

  • As the milk begins to flow, you may feel a distinct feeling of heaviness or tingling as the milk begins to spray or drip out. Some mothers never feel a distinct sensation when their milk lets down, while for others it is strong enough to be almost painful. Some mothers don't feel the sensation in the early days of nursing, but will feel it later on. As long as your baby is getting milk, you know it is letting down. You will also experience milk leaking from the other breast as it lets down on one side. This is normal, as your milk always lets down on both sides at once (your body doesn't know you're not nursing twins!) Another sign that your milk is letting down is 'afterpains', which are abdominal pains similar to menstrual cramps. These cramps are caused by the release of the hormone oxytocin. The same hormone that makes your milk let down also causes your uterus to contract. The afterpains may be mild or severe, and are usually stronger in women who have had children before than in first time mothers. The uterine cramping, while not pleasant, is a sign that your uterus is contracting and returning to its pre-pregnant state. This occurs faster in nursing mothers than in formula feeding mothers--another advantage of breastfeeding. Your uterus will continue to shrink for about six weeks, but the afterpains are usually only uncomfortable for the first few days after birth. Don't be surprised if the cramping is much stronger while your baby nurses--that's a sign that your milk is letting down effectively. You may also experience increased blood flow during the first few days after birth while your uterus is contracting, especially during nursing when your milk lets down.

  • Place the container under the breast and lean over it. Grasp the areola by putting your thumb on the top and your forefinger on the bottom. Press the breast tissue back toward your chest and squeeze your thumb and finger together, rotating forward, just behind the areola. Do this a few times, then move the fingers half an inch to the left or right and compress again. Continue rotating around the areola until you reach all around the breast. You may want to use your other hand to alternate massaging and compressing.

  • Another method is to hold the breast with your thumb on the top of the areola, and the other four fingers cupping the breast from underneath, with your little finger touching your ribcage. To start expressing, begin a wave-like motion by pushing your little finger gently into the breast, followed by the fourth, third, then index finger while you compress the tissue with your thumb from above. Rotate until all areas of the breast are compressed.

  • With both these techniques, repeat the procedure on the other breast once you have rotated all around the first breast. You may want to alternate breasts more than once, which encourages multiple let downs.

While there is always some milk in your breasts, it is easiest to hand express when your breasts are full, especially in the morning.

The techniques described above may sound complicated, but they really aren't once you practice a little. Some mothers are very successful at manual expression, but others find it frustrating and tiring. It is not a good method to use on a regular basis, or to use after feedings when the breast is relatively empty. It usually takes at least 20-30 minutes to empty the breast with hand expression or manual pumping.

I often talk to mothers who are trying to use hand expression or manual pumps and they say things like, "I sat there for half an hour, and only got one ounce of milk. What's wrong with me?" The answer is "nothing". The problem is that they are only getting out the small amount of foremilk that collects between feedings, but aren't getting their milk to let down. If the milk is not letting down, you will see drops of milk slowly dripping out, but not spraying or spurting out. If you are pumping and only getting drops (and this applies no matter what type of pump you are using), stop and go back to the suggestions above to get your milk to let down. Continuing to pump or express while only getting drops will just frustrate you and make you tense, making it less likely that your milk will let down and flow freely.

Manual pumps are portable and relatively inexpensive. They are fine for occasional use, or for the mother who has an abundant milk supply and an efficient let-down reflex. All manual pumps work on the principle of creating a vacuum that creates pressure which causes milk to flow from an area of high pressure in the breast to an area of low pressure in the pump. It is important to remember that no breast pump is as efficient as the baby at removing milk, and manual pumps are generally less effective than electric ones.

There are three types of manual pumps: the rubber bulb pump which looks like a bicycle horn (avoid these - they are terribly inefficient, hard to clean, and can damage your breast tissue), the cylinder type which consists of two cylinders, an outer one and an inner one, which generates a vacuum when it is pulled in and out, and the squeeze handle pumps. Squeeze handle pumps generate suction when you squeeze and release a handle. They can be very effective, but can cause your wrist and arm to tire quickly with the repeated use, so are not a good choice if you have arm or hand problems such as arthritis or carpal tunnel syndrome.

While there are many brands of manual pumps on the market, I like the Medela's new ManualEase the most.

Make sure that the flange (the funnel shaped part) of the pump fits correctly. Some, such as the Medela pumps, come with adapters that fit inside to adjust for different size breasts and nipples. The nipple and areola should be surrounded by the flange. The flange should not extend way past the areola, and the areola should not extend way past the flange. If the flange fits correctly, part of the areola and all of the nipple should slip comfortably and easily into it. While Medela's pumps have a flange size that fits most mothers, (most don't need to use the plastic inserts), some mothers with very large nipples may need the PersonalFit Breastshield kit, which can be used with any of Medela's pumps and contains two different size flanges.

When you are ready to start pumping, moisten the flange (or you may want to use a few drops of olive oil) and center the nipple in the flange. Follow the instructions on the pump, because the technique will differ depending on which type of pump you are using. If the pump has an adjustable vacuum (and it should--all of Medela's pumps do), start out on minimum and increase as your milk starts flowing. Most pumps will give the better results on the higher suction settings, but if your nipples are sore or your breasts are tender due to engorgement or infection, keep the pump set on the lower setting. Some mothers get better results with medium suction levels and higher cycling speeds if you are using a pump like the Pump In Style which allows you to adjust the cycling.

Follow the manufacturer's instructions on cleaning the pump. Only the parts that actually touch the milk need to be cleaned, and usually hot soapy water or running them through the dishwasher is all that is needed, although they can be boiled as well.

The earlier suggestions about encouraging let-down and alternating breasts apply to manual as well as hand pumping.

There are a number of electric pumps on the market. Some are terrible, some are not so bad, and some work quite well. In general, the small semi-automatic pumps like the Gerber and Evenflo are not very effective. Because of their small size, relatively low cost, and battery options, these are big sellers in the department and baby stores. Many people buy them without realizing that there are tremendous differences in electric pumps. Anyone who has told you that she tried and electric pump and it didn't work, or it hurt, was probably talking about one of the small semi-automatic models rather than the more expensive hospital or professional grade models.

Some of the problems with these pumps (besides the fact that most of them just don't work well and many mothers say they hurt) are the fact that they are noisy, and use up batteries quickly, so they become expensive to operate. If you do run a pump on battery power, use alkaline batteries, and replace them frequently because as they wear down, the pump will take longer and longer to generate suction and you will get fewer cycles per minute.

I have heard so many negative comments from mothers throughout the years about these pumps that I can only recommend one--the Medela MiniElectric. Most small electric/battery type pumps do not cycle automatically. You have to put your finger on a hole or a button and release it repeatedly to create intermittent suction. Since babies nurse about once every second, ideally a pump should cycle between 40 and 65 times every minute. With these semi-automatic pumps, it is difficult to get them to cycle more than 10 times per minute. The MiniElectric cycles automatically about 32-34 times per minute, which much more closely simulates a baby's sucking pattern. Because this is still not as many cycles per minute as a baby generates, the MiniElectric is only recommended for occasional use. If you are a stay at home mom, and want to pump every now and then so you can have relief bottles, this may be the right pump for you. It is much more efficient and easier to use than hand or manual expression, and is great for travel because of it's small size and battery option.

If you are going to be pumping regularly, or if time is an important consideration, you really need to be double pumping with a larger, more efficient (and more expensive) professional or hospital grade pump. In situations where you must be separated from your baby for extended periods of time, such as a premature infant, and the only stimulation your breasts will receive is from the pump, you ideally should use a hospital grade pump such as Medela's 015 Classic. This type of pump is much heavier than other pumps, and would cost about $1450.00 to purchase, so most mothers rent it. It provides the best possible stimulation for maintaining your milk supply when medically indicated.

Some insurance plans will pay the cost of rental for hospitalized infants. Call Medela's toll free number (1-800-TELLYOU) to find a rental station in your area.

There are two other professional grade Medela pumps available for rental or purchase that provide adequate pressure and stimulation for frequent, long term use, and allow double pumping. These are the 016 Lactina Select (available for rental) and the PumpInStyle (available for purchase). All three types of pumps (015, 016, and PumpInStyle) meet the criteria for optimal suction pressure and cycling, and allow you to single or double pump and adjust the suction levels. The Lactina and the Pump In Style also allow you to adjust the cycling speed.

When a baby nurses he generates about 200-250 millimeters of negative pressure and sucks 45-60 times per minute. Pumps that provide pressure levels above the high 200s can cause pain, and levels below 150 are not effective at removing milk. The most efficient pumps create pressure levels between 200-230 millimeters and cycle about once every second or so. Medela's ManualEase, MiniElectric, PumpInStyle, 015 Classic and 016 Lactina Select all have pressure levels around 220 when set on maximum.

Double pumping is an important feature. Not only does it cut your pumping time in half (from 20-30 minutes with single pumping) to 10-15 minutes or less, but your prolaction levels are higher when you double pump, so you actually produce more milk in less time. This is especially important when you are pumping frequently, or when you are working or in school and have limited break time in which to pump.

Don't be surprised if you get more milk from one breast than the other when you double pump, because each breast functions independently of the other. Some mothers will get 3 or 4 times as much from one breast as the other, and some will notice only a subtle difference in the amount they get from each side. It would be unusual for each breast to produce exactly the same amount.

The 016 Lactina Select is portable and popular with working mothers. It costs over $700 to purchase, so most mothers rent it instead. Some mothers prefer to rent rather than purchase a pump because they want to try a professional-grade pump before purchasing one, or because they only plan to nurse for a short time.

The Lactina can be used with optional vehicle lighter adapters or Power Packs if you need to pump in your car or don't have access to an electric outlet. See product information for more information about these convenient options, and where to rent a Lactina.

The PumpInStyle is the only portable, autocycling, professional-grade breastpump for sale to mothers. I think it is by far the best pump on the market, and it is the pump most popular with mothers. It is an excellent choice for mothers who want convenience, portability, and efficiency. It's a great investment, especially if you intend to breastfeed long-term or are planning to have more children.

Guidelines for Storing Human Milk

(These guidelines apply to milk that will be given to healthy, full-term babies. If you are expressing milk for a sick or premature baby, check with your doctor or hospital staff regarding collecting, handling, and storing your milk).


Human milk can be safely stored in glass, hard plastic bottles, plastic freezer bags, or polyethylene milk storage bags especially designed for storing breast milk. While you have many options for storing your milk, I recommend the CSF bags made by Medela. They are pre-sterilized and lined with nylon that keeps fat cells from adhering to the sides. They are designed to protect the nutrients and anti-infective qualities of human milk. They are thicker than the bottle liners sold for use with disposable bottle systems, which may split during freezing and may cause a decrease in the antibodies and fat which adhere to the sides of the bags. They also take up less room in your freezer, and the milk thaws faster than milk frozen in hard containers. There has been a controversy for years over glass versus plastic containers for human milk. While glass is good for storing frozen milk because it is non-porous, it has disadvantages. The most obvious is that it can break, and you don't want to waste any of your 'liquid gold'. Don't use glass bottles if you are going to store the milk for less than 24 hours, because some of the white blood cells will adhere to the glass, but not to plastic. Since the cells detach after 24 hours, the composition (glass versus plastic) doesn't matter if you are freezing the milk. Since many of the white blood cells are destroyed by freezing, it makes sense to refrigerate milk whenever you will be using it within 8 days, and use CSF bags especially designed for storing human milk when you must freeze it. They protect the immune factors as well or better than glass, they don't break, they take up less room in your freezer, and they thaw out faster. Plus, they are easier to find. Have you tried to buy glass bottles lately?

You may want to freeze your milk in ice cube trays. Clean the tray first with hot soapy water and air dry. Each cube is about an ounce, so you can pop out as many ounces as you want and put them into freezer bags. They are great to have on hand for snack or cereal feedings when you just need an extra ounce or two.

When storing milk in bottles, wash them in hot soapy water and air dry. Choose a top that fits well. You can boil them if you want to, but it isn't really necessary. CSF bags are sterile and don't require any preparation before use.

When milk is frozen, it expands, so leave about an inch at the top of the container to allow room for expansion.

Put only two to four ounces of milk in each container, or the amount your baby will take at a single feeding. Smaller quantities are easier to thaw, and you avoid waste this way. It's always good to have some smaller amounts on hand for snack feedings, or to offer if your baby finishes one feeding and is still hungry. You can add fresh milk to a container of frozen milk as long as there is less fresh milk than frozen. Cool the milk for 30 minutes first. For example, you can add 2oz. of fresh milk to 4oz. of frozen, but not 4oz. of fresh milk to 2oz. or frozen. You don't want it to thaw and then refreeze.

Label each container with the date it was expressed. If you are taking it to day care, put your baby's name on the label. Medela's CSF bags have a label area that stays flat even when the bag is full. Since the composition of human milk changes to meet your baby's needs as he grows, always use the freshest milk possible.

Storing Human Milk

Whenever it is possible, give your baby fresh milk that has been refrigerated, not frozen. Freezing kills some of the live cells and antibodies in human milk, but not all of them. Since formula doesn't have any of these anti-infective properties to begin with, frozen milk is still better for him than formula. If you are planning to use the milk within eight days, refrigerate it rather than freezing it.

Because human milk is a living substance, its antibacterial properties help it stay fresh longer than formula. How long you can store it depends on the temperature.

  • Freshly expressed milk can be stored at room temperature for up to ten hours. Colostrum or milk expressed within one week of delivery can be stored for twelve hours at room temperature. However, whenever possible, milk should be placed in the refrigerator soon after expressing.

  • Fresh milk can be kept in the refrigerator for up to eight days. Store it toward the back.

  • Fresh milk can be stored in a cooler with icepacks for up to 24 hours.

  • Fresh milk can be placed in a freezer compartment inside a fridge for up to 2 weeks. (These are usually only found in older type refrigerators).

  • Fresh milk can be kept in a self-contained freezer compartment for 3-6 months, depending on how often the door is opened. Store it toward the back.

  • Fresh milk can be stored in a separate chest type deep freeze for 6-12 months.

  • Milk that has been frozen and thawed can be kept in the fridge for 24 hours. Thawed milk should not be refrozen.

With all these guidelines, remember that fresh milk which has been stored at room temperature or in a cooler before being placed in the fridge or freezer may not keep as long. That's why you should always place milk in the fridge as soon as possible after expressing it.

New research indicates that milk that has been offered to a baby but has not been heated can be kept at room temperature for up to 4 hours, or 24 hours if you put it in the fridge right away. Once the milk has been heated, it can sit at room temperature for up to 2 hours, but then should be discarded. Milk that has been heated and offered to the baby can be refrigerated within 30 minutes and offered again for the next feeding, but discarded after that. These are the guidelines I've suggested to mothers for over 10 years, and have never heard of any problems.

When a refrigerator isn't available, put the milk in an insulated container with icepacks. The PumpInStyle comes with it's own built-in insulated container and icepacks, making it ideal for transporting milk home from work.

Handling and Thawing

Human milk may separate into layers of milk and cream during storage. Gently shake it to mix the fat that has separated.

Breastmilk may look bluish, greenish, yellowish, or brownish according to what you have eaten recently. Foremilk expresses at the beginning of a pumping session may look thinner and bluish, like skim milk. Hindmilk expressed later in the feeding may look thicker or creamier, and have a yellow tint. The yellow tint is especially pronounced during the first week or so of nursing while the milk still contains colostrum. Your milk may smell 'soapy' after it is frozen and then thawed. This is due to changes that occur during the freezing process, and is not harmful to the baby. Breastmilk isn't spoiled unless it smells really bad or tastes sour.

You can pump directly into refrigerated milk as long as you add the milk within 24 hours of when the original milk was expressed. If milk has been stored at room temperature, you can pump directly into it as long as you do it within eight-ten hours. You then need to use the milk as soon as possible.

If you plan to use the milk within 8 days, don't freeze it. If you do plan to freeze it, do so within 24-48 hours of expressing it. The sooner you freeze it, the better.

To defrost frozen milk, place it in the fridge the night before you're going to use it. This takes about twelve hours. If you need to thaw it quickly, run it under warm water that is gradually warmed, or place it in a bowl of water that is gradually warmed. Don't use hot water, and NEVER heat it in a microwave. This can destroy the live antibodies in the milk, and may also create 'hot spots' than can burn your baby's mouth, even though the container may not feel hot to the touch.

Many babies don't care if the milk is served cold right out of the fridge. It won't upset their stomach, and will save you or your caregiver a minute or two, which can be really important if your baby is frantically hungry. If you want to try cold milk, be sure to run the nipple under warm water if it has been refrigerated. Most babies dislike cold nipples more than they dislike cold milk.

How Much Milk to Leave for Your Baby

Average intake by age:

  • birth to two months: 2-5 ounces per feeding
  • two to four months: 4-6 ounces per feeding
  • four to six months: 5-7 ounces per feeding

Average intake by weight: The average baby who isn't eating anything but milk needs about two and a half ounces per pound of weight. Some babies need more, some need less in order to gain weight adequately. A ten-pound baby needs about 25 ounces in twenty-four hours (round up an ounce or two to be on the safe side-- say 27 ounces) which means that if he eats eight times in 24 hours, he would need a little over three ounces at each feeding. You'll get a feel for how much he will eat at each feeding as he begins to take bottles on a regular basis.

FYI: Human milk is not considered a bio-hazardous body fluid like blood or saliva, and OSHA and the CDC agree that it does not have to be treated as such.

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