New Study: Exclusive Breastfeeding Can Support Infant Growth to 6 Months of Age

A new study published this week in the journal Pediatrics found that exclusive breastfeeding up to six months provides enough calories for infants.

 

Quick and Dirty Summary:

This study addressed two common concerns about breastfeeding:  1) Many moms simply can’t produce enough milk for their babies; and 2) Exclusive breastfeeding, while adequate in younger infants, may not provide enough calories for babies up to 6 months of age.  The data from this study indicate that when moms are given breastfeeding support, milk production is not a limiting factor and provides enough calories for normal growth, even in 6-month-old infants.  However, this study was small and had several limitations (which I will discuss). 

 

How was this study conducted?

This was a longitudinal study of 50 mothers and their infants in Glasgow, Scotland.  All of these mothers intended to exclusively breastfeed (EBF) for at least 6 months and were recruited from breastfeeding support groups, so we can presume that they were already set up to succeed with breastfeeding.  EBF is defined by the World Health Organization (WHO) and in this study as giving the infant only breast milk for nutrition (no solids or formula), with oral rehydration, vitamins, minerals, or medicines allowed as needed.  60 mothers were recruited, but only 50 were still EBF at the first assessment around 15 weeks of age.  Assessments included measurements of infant growth, milk intake, total energy intake, and milk energy content.  Mothers also completed questionnaires and infant behavior diaries in order quantify the number of feedings and total time spent nursing.  These measurements were all repeated at 25 weeks of age (6 months).  At this second time-point, 3 mothers had dropped out of the study and 41 mothers were still EBF.  The remaining 6 mothers had begun feeding their babies some solid foods. 

How, you might ask, did the researchers manage to measure milk intake in nursing babies?

Excellent question.  They used a technique called the doubly-labeled water method, which involves feeding the baby a tiny and safe dose of stable isotope-labeled water (²H₂¹⁸O) and then collecting samples of their pee (which is easy enough to do when you change a diaper) to measure how long it takes those isotopes to come out.  Then they did a bunch of calculations.  Really.  Trust me when I tell you that this method is safe, non-invasive, and pretty much the best way to measure milk intake in nursing babies.  I’ve actually had a little experience  (in a previous life) using this method in nursing bottle-nosed dolphins.

What are the most important findings of the study?

-The exclusively breast fed infants in this study grew just fine, right in line with the WHO Child Growth Standards.  EBF to 6 months didn’t set them back in their growth curves.

-Milk intake was slightly but significantly higher at 25 weeks compared with 15 weeks (997 vs. 923 grams; P=0.001), showing that milk production increased to meet the increasing demands of the infant.  Milk energy content (as in calories per liter) did not change between time points.

-Moms reported breastfeeding 8-9 times per day at both 15 and 25 weeks, but time spent feeding decreased from 173 minutes per day at 15 weeks to 140 minutes at 25 weeks.  That means that at 25 weeks of age, babies were drinking more milk but doing so more efficiently than at 15 weeks.  No surprise there.

 

-There was no difference in infant weight or milk intake at 25 weeks between the EBF infants and the 6 that had started solid foods.  The moms of these babies said they started solids because their babies seemed ready.

What can we conclude from this study?

The study shows that in most women with good breastfeeding support, infant milk intake is sufficient to support normal growth with EBF for 6 months. 

The authors of the study assert that their findings support the recommendation that all babies should be EBF for the first 6 months, but there are some problems with jumping to that conclusion… 

What are the limitations of the study?

-10 of the 60 moms initially enrolled in the study were not still exclusively breastfeeding at 15 weeks, and the study authors don’t tell us what happened to those 10 women.  Did they stop breastfeeding or supplement with formula because of a fear, real or not, that they weren’t producing enough milk?  We just don’t know.

-The mothers in this study were older (mean age 33) and more affluent than the average mom.  They were highly motivated to exclusively breastfeed and had good support to do so.  Just guessing, but this type of mom is also more likely to take good care of herself and have support at home to do that.  All of those factors might impact her breastfeeding success.

-The 6 babies that started solid foods prior to 6 months had similar caloric intake from milk as the EBF babies.  These babies were also getting some additional calories from food, but the study did not report this.  It is possible that these babies were truly ready for solids before 6 months and needed the added energy from solids, in addition to breastmilk.  The authors don’t address this possibility.  

-This study only looked at calories from milk intake.  It doesn’t consider micronutrients such as iron and zinc that may become limiting at this age without the addition of some solid foods in the diet. 

My take: 

This study shows that exclusive breastfeeding to 6 months can provide enough energy to support normal growth in babies.  However, the mothers in this study were highly-motivated and had great support for breastfeeding.  We don't know why 10 women dropped out of the study or if the babies consuming solid foods actually needed the additional calories from that food. Due to these limitations, the results of this study may not apply to the general population.

It is easy to over-simplify the results of a study like this, but when we really look at the data, we find that it just isn’t that simple.  Unfortunately, most science isn’t.

The perception of low milk supply remains a major barrier to exclusive breastfeeding, and more work needs to be done to show whether or not this is a physiological or psychosocial problem. 

What do you think?  Did you or a friend have a problem with low milk supply?  There is nothing worse than thinking that your baby is hungry and not being able to feed her!

Exploring and Enjoying Food with Baby

At almost 10 months old, BabyC spends at least two hours per day in her high chair.  She loves finger foods and takes her time with them.  For me, this is a great time to catch up on the dishes or work on preparing a meal, all the while chatting with BabyC, replenishing her high chair tray, and listening to some music together.   

As much as I value that productive, multi-tasking time, I’ve been making a real effort to prepare food for both of us and sit down to enjoy meals with her.  Due to his hectic work schedule, my husband is rarely both home and awake during our meals, but we’re sitting down to eat with Dad when we can, too.  I want BabyC to know that mealtime is family time.

 

BabyC examines the ingredients of lasagna, a dish we can both enjoy.  BabyC now notices when I have something on my plate that she doesn’t have, so it is nice to eat the same foods.

Mealtime is also a great time to explore the tastes and textures of foods.  We’ve been having a lot of fun with this lately.  I pull the high chair up to the counter so that BabyC can watch me prepare food.  Fruits have proven to be the most exciting.  Try handing your baby a fresh peach, a kiwi fruit, or even plopping a whole cantaloupe on her tray.  Let her smell it and feel the texture of the skin.  When I put the cantaloupe in front of BabyC, she was clearly impressed with the weight of it.  She tried to pick it up with both hands, but it was too heavy for her.  She looked up at me inquisitively, and I agreed with her, “That is a very heavy cantaloupe, isn’t it?”

Next, I cut the fruit open on the counter while BabyC watches.  Then I show her the inside of the fruit and let her touch it and smell it again.  By this point, BabyC is usually really excited and ready to eat.  Finally, I cut the fruit into pieces that are a little more manageable for her, and we both sit down to enjoy eating together.  What a great way to engage all your baby’s senses!

If this was the first time you’d seen the inside of a cantaloupe, wouldn’t you be interested in exploring it further?

To further cultivate our baby’s understanding of food, we have also visited several local u-pick farms this summer.  Many of us will take our kids to a pumpkin patch in a month or so for some classic photo ops.  Pumpkins are really fun, but right now is harvest time for lots of foods that your kids already know and love, so it is the perfect time to visit a local farm and learn more about where your food comes from.  We visited Detering Orchards just outside of Eugene last week.  They have lots of u-pick fruits and vegetables in addition to a gorgeous farmstand where you can buy pre-picked produce.  What I love about this farm in particular is that their crops are so diverse.  We went out to pick apples but then stumbled into some gorgeous fields of cabbages, broccoli, and beets, and then we wandered over to the peach trees. 

We also had a 2- and a 4-year-old with us, and they loved checking out the veggies, especially hunting for ripe beets.  (I’m not sure the beets were supposed to be u-pick, but how can you deny a 4-year-old that is really excited about beets?)  BabyC had a great time, too.   

I’m sure BabyC’s understanding of where her food comes from is pretty rudimentary at this point, but I like to think that there is now some wiring in her brain associating delicious food with the texture of dirt and the fragrance of an orchard.  In fact, I’m pretty sure that she thinks dirt is a food right now, because it goes straight in her mouth. 

Responsible mama note:  If you are going to do some tasting of freshly-picked foods, be sure to check the farm’s policy on spraying pesticides and choose an organic farm to be safe.  Also, be aware that there are risks of foodborne illness associated with eating even organic foods without washing them first.  This post depicts irresponsible parenting behavior – eating produce fresh off the farm.  I grew up on a farm where we ate straight out of the garden all the time, but I should really take this more seriously because I hate the thought of my kid getting sick!  It is best to pick first and save the tasting until both food and hands have been washed.

 

Practical Ways to Increase Iron in Your Baby’s Diet

I mentioned in my last post (Does My Baby Get Enough Iron?) that I have been worrying about my 9-month-old’s iron nutrition.  Iron deficiency can cause lasting delays and deficits in cognitive and behavioral development, and I don’t want to go there.

First, let’s consider if your baby is actually at risk for iron deficiency, because why fret about something that isn’t a problem?  You have enough to worry about.

If your baby is less than 6 months of age, he probably has enough iron.   Babies are usually born with sufficient iron stores to last them for about the first 4-6 months of life.  There are some exceptions:  If your baby was born preterm or small for his age or if you have diabetes, he may have been born with lower iron stores, in which case your pediatrician will usually prescribe iron drops for your baby.  In addition to the iron your little one is using from his iron stores, he will also get some iron from breast milk or formula during the first six months.  Breast milk doesn’t contain much iron, but infants are very efficient at absorbing it.  If your baby is drinking iron-fortified formula, he is getting lots of additional iron.  There are some “low iron” formulas on the market, so make sure yours is not one of them.

Around 6 months of age, the iron stores are depleted, and your 6- to 12-month-old baby needs to be consuming about 11 mg of iron per day.  A formula-fed baby will continue to get lots of iron from formula, in addition to complementary foods.  However, if your baby is 6 months or older, mainly breastfed, and doesn’t eat at least two servings of fortified baby cereal or meat per day, he could be at risk for iron deficiency.  Toddlers (1-3 years) need 7 mg of iron per day.  Toddlers don’t require as much iron as babies, because toddlers don’t grow quite as fast.  If your toddler is consuming cow’s milk and not much in the way of iron-rich foods, he could still be at risk for iron deficiency.

At 9 months old, my BabyC falls into the “at-risk” category.  She is breast-fed, doesn’t like the baby cereals, and only eats a little bit of meat, so I set about trying to find other ways to sneak iron into her diet.  Here is what I found:

5 Ways to Increase Iron in Your Baby’s Diet:

1.    Love your fortified cereals!  BabyC won’t have anything to do with baby cereals (and I’ve tried several varieties), but she will eat some regular fortified oatmeal.  This doesn’t have as much iron as baby cereals, but it still gives her a nice dose.  Cream of Wheat and Malt-O-Meal are also good options.  Look for cereals that state in the Nutrition Facts label that they provide at least 45% of the daily value for iron.  Note that if the cereal is not made specifically for babies, this refers to the adult requirement and an adult-sized serving, but it is still an indicator that the cereal is fortified.  If your baby will eat dry cereals, such as Cheerios, these are usually fortified as well.  Unfortunately, many of the “natural” cereal brands are not fortified, so double-check the labels again for that 45% of daily value. 

2.     Cook with fortified cereals.  I have made some delicious pancakes for BabyC using all of the many varieties of baby cereal that she has refused to eat the conventional way.  I used this recipe found at wholesomebabyfood.com.  The recipe makes about 24, 2-inch pancakes, and when you tally up the iron sources (baby cereal, flour, egg yolks), you end up with 1.25 mg iron per pancake.  Use water in the recipe instead of milk to avoid the inhibiting effect of dairy on iron absorption.  BabyC can easily eat 3-4 of these at breakfast (especially if they have blueberries!), and at that rate she’s already met almost half of her iron requirement.  I make a big batch and then freeze them in baggies of 3-4 so it is easy to pull out a serving to thaw.  I’m exploring other recipes that will turn fortified cereals into finger foods.  Next up is Malt-o-Meal muffins!  Also, consider mixing some baby cereal into savory foods like meatballs.

3.     Include a source of vitamin C.  Several studies have shown that including vitamin C in a baby’s meal can at least double the absorption of iron from cereals and legumes.  I give BabyC Tri-Vi-Sol drops  (or a generic version) at breakfast, which contain 35 mg of vitamin C.  Other baby-friendly sources of vitamin C include citrus, strawberries, cantaloupe, kiwifruit, raspberries, broccoli, bell peppers, and potatoes.  BabyC loves those little Clementine oranges, and each of these contains about 36 mg of vitamin C.  Pair a good source of vitamin C with meals containing cereals and beans to maximize the iron your baby absorbs from those foods.

4.     Limit dairy with meals.  The calcium in cow’s milk inhibits iron absorption, so avoid feeding dairy with high-iron meals.  Instead, feed cheese and yogurt as a between-meal snack.  BabyC loves cheese, and the calcium is good for her, but separating it from a meal means that it is less likely to interfere with her iron absorption.  And above all, don’t give your baby cow’s milk before age 1 – stick with either breast milk or an iron-fortified formula.

5.    Introduce a variety of iron-rich foods, including grains, meats, beans, and veggies.  I know that BabyC isn’t going to get all of her iron from cereal, so I make sure that she has opportunities to eat a variety of iron sources throughout the day.  And remember that you may have to offer a food to your baby 5 or 6 times before he’ll really eat it, so keep trying. 

The table below will give you some good ideas of iron-rich foods that you can incorporate into your baby’s diet.  Pay attention to the serving size in the table, and remember that all of the food sources of iron need to add up to 11 mg of iron per day for a 6- to 12-month-old baby or 7 mg for a 1- to 3-year-old toddler.

What are your baby’s favorite iron-rich foods? 

Finger-Food-Friendly Sources of Iron

	Serving size	Iron per serving (mg)
Animal Sources
Chicken liver	1 oz	3.32
Beef liver	1 oz	1.76
Sardines	1 oz	0.83
Ground beef	1 oz	0.55
Egg yolk (avoid whites until 1 yr)	1 large (17 g)	0.46
Chicken thigh	1 oz	0.38
Chicken breast	1 oz	0.29
Grains
Baby cereal	5 Tbs	5.95
Fortified oatmeal	5 Tbs	3.66
Cheerios	1/4 cup (7 g)	2.23
Amaranth	1/4 cup	1.29
Quinoa	1/4 cup	0.69
Barley	1/4 cup	0.52
Pasta	1/4 cup	0.45
Wheat germ	1 Tbs	0.45
Whole wheat bread	1/2 slice	0.43
Legumes
White beans	1/4 cup	1.66
Lentils	1/4 cup	1.65
Kidney beans	1/4 cup	1.30
Black beans	1/4 cup	0.90
Chick peas	1/4 cup	0.90
Tofu	1/4 cup	0.67
Vegetables
Spinach	1/4 cup	0.93
Green peas	1/4 cup	0.61
Kale	1/4 cup	0.29
Broccoli	1/4 cup	0.26
Green beans	1/4 cup	0.22

Values in this table were adapted from the USDA National Nutrient Database.

© Alice Callahan, PhD