Can I mix breast milk and formula?

Expert Answers

Jan Barger, lactation consultant

While there’s nothing wrong with mixing breast milk and formula in the same container, it’s not recommended simply because you don’t want to waste a single drop of your precious breast milk. Formula from a bottle that your baby has drunk from must be discarded within an hour of preparation. Breast milk, on the other hand, will “keep,” refrigerated, for a number of hours in a bottle that’s been fed.

So, for example, if you mix 2 ounces of expressed breast milk with 2 ounces of formula, and your baby only drinks 2 ounces altogether, you’ll have to throw the leftovers out, wasting some of the breast milk. To avoid this kind of waste, a good plan is to feed your baby whatever breast milk you’ve expressed, and then follow that up with couple of ounces of formula if you need it.

Some mothers mix powdered formula with their breast milk in order to increase the calories their baby gets during a feeding. Please do not do this! Not only does it change the composition of the breast milk, but the micronutrients in the formula will become so much more concentrated that it can be very hard on your baby’s immature kidneys. Always follow the exact directions on the can of powdered or concentrated formula, and never mix formula with anything but distilled water.

Bottle-feeding basics

Highlights

How often should I feed my baby?
Do I need to sterilize the bottles?
Can I mix breast milk and formula?
What’s the best way to warm a bottle?
How can I make sure my baby is drinking comfortably?

How often should I feed my baby?

Most experts agree that you shouldn’t follow a rigid feeding schedule in the early weeks, though you may be able to work out an approximate pattern within a month or two.

Offer your breast or the bottle every two to three hours at first or as your baby seems hungry. Until your baby reaches about 10 pounds, she’ll probably take one to three ounces per feeding. Don’t force more than she seems ready to eat. Your baby’s doctor should advise you about suitable amounts for your child as she grows.

Do I need to sterilize the bottles?

Before you first use new bottles, nipples, and rings, you should sterilize them by submerging them in a pot of boiling water for at least five minutes. Then allow them to dry on a clean towel. After that, a good cleaning in hot, soapy water, or a cycle through the dishwasher is sufficient. One caveat: If you have well water, repeated sterilization of the bottles may be best.

You can find some handy bottle gear, such as dishwasher baskets for nipples, rings, and bottle caps, and special bottle drying racks, at most baby supply stores.

Find out how to choose bottles and nipples and when to replace them.

Can I mix breast milk and formula?

While there’s nothing wrong with mixing breast milk and formula in the same container, it’s not recommended simply because if you’re pumping and supplementing with formula, you don’t want to waste a single drop of your precious breast milk. To avoid this, a good plan is to feed your baby whatever breast milk you’ve expressed, and then follow that up with couple of ounces of formula if you need it. Find out more.

What’s the best way to warm a bottle?

There’s no health reason to feed a baby warmed milk, but your baby may prefer it. When you’re ready to feed your baby, you can warm a bottle in a pan of hot — not boiling — water, or by running it under the tap. You can also buy a bottle warmer designed for this purpose.

If your baby is accustomed to drinking bottles at room temperature or slightly cold, you save yourself the time and hassle of preheating bottles, especially when she’s crying to be fed.

Never use a microwave to heat a bottle of breast milk or formula. Since a microwave oven heats unevenly, it can create hot pockets, leading to burns. It can also cause nutrients to break down.

How can I make sure my baby is drinking comfortably?

Like so much with babies, you’ll need to listen and observe. If you hear a lot of noisy sucking sounds while she drinks, she may be taking in too much air. To help your baby swallow less air, hold her at a 45-degree angle. Also take care to tilt the bottle so that the nipple and neck are always filled with breast milk or formula.

Never prop a bottle — it can cause your baby to choke. Besides, bottle-feeding, like breastfeeding, can be a wonderful time for nurturing your baby by holding her close. So take feeding time as an opportunity to snuggle and bond.

How breastfeeding benefits you and your baby

Highlights

Breastfeeding protects your baby from gastrointestinal trouble, respiratory problems, and ear infections
Breastfeeding can protect your baby from developing allergies.
Breastfeeding may boost your child’s intelligence
Breastfeeding may protect against obesity later in life
Breastfeeding may protect your baby from childhood leukemia
Breastfeeding may protect your baby from developing type 1 diabetes
Breastfeeding may protect preemies from infections and high blood pressure later in life
Breastfeeding may lower your baby’s risk of SIDS
Breastfeeding helps you lose weight
Breastfeeding can lower your stress levels and reduce postpartum bleeding
Breastfeeding may reduce your risk of some types of cancer
Breastfeeding may protect against osteoporosis later in life

You’re probably well aware that breast milk is best for your baby, but did you know that the benefits of breastfeeding extend well beyond basic nutrition? In addition to containing all the vitamins and nutrients your baby needs in the first six months of life, breast milk is packed with disease-fighting substances that protect your baby from illness. That’s why the American Academy of Pediatrics recommends exclusive breastfeeding for the first six months. And scientific studies have shown that breastfeeding is good for your health, too.

Here’s a look at some of the most important benefits you and your baby may derive from breastfeeding:

Breastfeeding protects your baby from gastrointestinal trouble, respiratory problems, and ear infections
Numerous studies from around the world have shown that diarrhea, lower respiratory illnesses, and ear infections happen less often in breastfed babies, and are less severe when they do occur. Exclusive breastfeeding (meaning no solid food) for at least six months seems to offer the most protection.

Researchers have found that immune factors that are present in colostrum (the first milk your body produces) guard against invading germs by forming a protective layer on your baby’s mucous membranes in his intestines, nose, and throat. The main immune factor at work here is secretory IgA (immunoglobulin A). It’s present in large amounts in colostrum – which is why it’s important to start nursing your baby right after birth – but is also found in lower concentrations in mature milk.

Breastfeeding may also protect your baby from developing inflammatory bowel disease later in life. Several studies have documented a link between a lack of breastfeeding in infancy and later development of Crohn’s disease and ulcerative colitis.

Breastfeeding can protect your baby from developing allergies.
Several studies have found that breastfeeding for six months or more makes it less likely that your baby will go on to develop food or respiratory allergies. At least one study has found that this protection appears to last well into adolescence. Another study found that preterm infants from families with a history of allergies had a lower risk of developing eczema than their formula-fed peers. A third study found that exclusive breastfeeding for at least the first four months after birth reduced a child’s risk of developing asthma by age 6.

Scientists think that the fatty acids and immune factors such as IgA in breast milk prevent allergic reactions by stopping large foreign proteins from getting into a baby’s system. (Proteins in cows’ milk are one of the most common allergens, which is one reason that babies who are fed cows’ milk-based formulas tend to have more allergic reactions than breastfed babies.)

Breastfeeding may boost your child’s intelligence
Several studies have found a possible connection between breastfeeding and higher IQs. Babies breastfed for six months or more seem to have the most advantage, Experts say that the emotional bonding that takes place during breastfeeding probably contributes to some of the increase, but that the fatty acids in breast milk may play the biggest role in a baby’s brain development.

Breastfeeding may protect against obesity later in life
Whether or not breastfeeding has any effect on a child’s weight later in life has been a matter of debate for some time. In May 2005, after conducting a review of 61 studies related to infant feeding and later obesity, researchers concluded that early breastfeeding is linked to a reduced risk of obesity – but they note that more study is necessary to determine just how strong that link is.

Experts think that breastfeeding may affect later weight gain for several reasons: Breastfed babies are better at regulating their feedings, leading to healthier eating patterns as they grow. Breast milk contains less insulin than formula (insulin stimulates the creation of fat). And breastfed babies have more of the protein hormone leptin in their system, a substance that researchers believe plays a role in regulating appetite and fat. Also, compared with breastfed babies, formula-fed infants gain weight more rapidly in the first weeks of life. This rapid weight gain is associated with later obesity.

Breastfeeding may protect your baby from childhood leukemia
Studies have shown that breastfeeding can lower a baby’s risk of developing both acute lymphoblastic and acute myeloid leukemia. Scientists don’t know exactly how breast milk reduces the risk of these childhood cancers, but they think antibodies in breast milk may give a baby’s immune system a boost. Research into this question is ongoing.

Breastfeeding may protect your baby from developing type 1 diabetes
Breastfeeding for more than six months appears to reduce a child’s risk of developing insulin-dependent (type 1) diabetes. In one study, children who were breastfed for less than three months and exposed to cows’ milk before 4 months had about 1.5 times the risk of developing the disease. It’s not clear exactly how breast milk protects against this disease, although researchers theorize that immune factors in breast milk play a role.

Breastfeeding may protect preemies from infections and high blood pressure later in life
Breast milk seems to offer special protection for premature babies. One study found that very low-birthweight babies nourished by breast milk had fewer serious blood infections and meningitis than those given formula. Another study found that preemies given breast milk were less likely to have high blood pressure by the time they were teenagers.

Breastfeeding may lower your baby’s risk of SIDS
There’s no conclusive evidence that breastfeeding reduces your baby’s risk of SIDS (sudden infant death syndrome) per se. Some studies have found a link between lowered rates of SIDS while others have not. What’s clear is that breastfeeding can help prevent respiratory and gastrointestinal infections that may be related to SIDS.

Breastfeeding helps you lose weight
Nursing your baby can help you shed pounds more quickly, especially during the first year. This is because your body burns calories while it makes breast milk.

Breastfeeding can lower your stress levels and reduce postpartum bleeding
Because nursing triggers the release of the hormone oxytocin in your body, you’re more likely to feel relaxed while breastfeeding. Numerous studies in animals and humans have found that oxytocin promotes nurturing and relaxation.

One such study found that women who had high amounts of oxytocin in their system (50 percent of breastfeeding moms compared with 8 percent of bottle-feeding moms) had lower blood pressure after being asked to talk about a stressful personal problem. Oxytocin also helps your uterus contract back to size after birth, resulting in less postpartum bleeding.

Breastfeeding may reduce your risk of some types of cancer
Numerous studies have found that the longer women breastfeed, the more they’re protected against breast and ovarian cancer. For breast cancer, nursing for at least a year appears to have the most protective effect. It’s not entirely clear how breastfeeding helps, but structural changes in breast tissue caused by breastfeeding and the fact that lactation suppresses the amount of estrogen your body produces may play roles. Researchers think the effect on ovarian cancer may be related to estrogen suppression as well.

Breastfeeding may protect against osteoporosis later in life

There’s conflicting evidence about the connection between breastfeeding and bone density. It’s apparent that lactating women do lose some bone density when they start breastfeeding, probably due to a calcium deficiency or low estrogen, but those losses are recovered during or after weaning. Two studies show that breastfeeding may actually improve a woman’s bone density in the long run and reduce the risk of hip fractures in old age.

How to start breastfeeding

The first time you hold your newborn in the delivery room, put his lips to your breast. Your mature milk hasn’t come in yet, but your breasts are producing a substance called colostrum that will help protect your baby from infection.

Try not to panic if your newborn seems to have trouble finding or staying on your nipple. Breastfeeding is an art that requires patience and lots of practice. No one will expect you to be an expert in the beginning, so don’t hesitate to ask a nurse to show you what to do while you’re in the hospital. (If you have a premature baby, you may not be able to nurse right away, but you should start pumping your milk. Your baby will receive this milk through a tube or a bottle until he’s strong enough to nurse.)

Once you get started, remember that nursing shouldn’t be painful. Pay attention to how your breasts feel when your baby latches on. His mouth should cover a big part of the areola below the nipple, and your nipple should be far back in your baby’s mouth. If latch-on hurts, break the suction — by inserting your little finger between your baby’s gums and your nipple — and try again. Once your baby latches on properly, he’ll do the rest.