The Virgin Gut?

As many of you who have read my blog in the past know, I am a big proponent of breastfeeding.  It is the one topic that I have written about the most on my blog.  New parents are constantly being given the message these days that "breast is best."  We hear about the usual benefits which include among other things:  "a protective effect against respiratory illnesses, ear infections, gastrointestinal diseases, and allergies including asthma, eczema and atopic dermatitis. The rate of sudden infant death syndrome (SIDS) is reduced by over a third in breastfed babies, and there is a 15 percent to 30 percent reduction in adolescent and adult obesity in breastfed vs. non-breastfed infants."  Organizations such as the World Health Organization and the American Academy of Pediatrics recommend exclusive breastfeeding for the first six months of life.  Despite these recommendations, many mothers still choose not to breastfeed and give formula to their baby instead.  Mothers may have legitimate reasons such as not having adequate breast tissue or not producing enough milk.  However, I think with our society's portrayal of breastfeeding, many mothers simply choose not to attempt it.  It is tiring and a lot of work.  

In the event of a mother not entirely convinced that "breast is best," there is yet another reason to attempt breastfeeding and that is the case for the "virgin gut."  This is something that I had not heard about with my first baby but am hearing more about with my second baby.  I first heard about it on some of the message boards that I frequent so I began doing some research.  I came across the following blog and an excellent paper written with lots of scientific citations.  Both of these are worth reading and go into great detail (better than I could do with my limited time for blogging) about the "case for the virgin gut."

I will do my best to "summarize" the theory.  A baby is born with a  "sterile" gastrointestinal tract.  "The gastrointestinal tract of a normal fetus is sterile. During the birth process and rapidly thereafter, microbes from the mother and surrounding environment colonize the gastrointestinal tract of the infant until a dense, complex microbiota develops."  The type of colonization is influenced by delivery (vaginal vs. cesarean) and perhaps most importantly by the method of feeding the baby (formula vs. breastfeeding). The gut flora of a formula vs. a breastfed infant is different.  It is believed that the flora that is established with breastfeeding can have protective effects for the baby throughout their lifetime.  Some believe that even one bottle of formula can upset this balance and may take weeks of exclusive breastfeeding to undo.

A part of this theory also addresses the "open gut."  Essentially, when a baby is born, their gastrointestinal system is "immature."  As a result, there are openings in the gut which allow large, potentially allergy causing proteins and disease causing pathogens to pass directly into a baby's blood stream.  It is theorized that mother nature "intended" for these openings for large maternal antibodies to pass into the baby's blood stream to protect the baby from disease.  The antibodies will also coat the lining of the gastrointestinal tract to confer passive immunity to a baby.  Feeding formula (which many contain cow's milk protein) or introducing solids before the age of six months is believed to increase the likelihood of the development of food allergies or illness.  It is believed that the "closing" of the gut occurs around six months which is why food should not be introduced until after a baby has reached six months of age.  This is especially important in babies with a family history of food allergies.  It is also believed that a baby is less likely to get sick after six months when a baby begins to produce their own antibodies and do not have to rely as much on passive immunity from the mother.

I had always been a believer in exclusive breastfeeding for the first six months of life.  My older son received one tiny bottle of formula when he was four days old since my milk was slow to come in because of a bad latch.  My second baby who just turned six months old yesterday has not had a single drop of formula.  He has only had breastmilk and nothing else (not even water) to drink.  Breastfeeding with either baby has not been easy but after reading about the "virgin gut," I am more than happy that I did.  I had a lot of pressure from well meaning family and friends to give my babies formula or start them on solids before six months of age.

I had a lot of allergies as a kid.  There are pictures of me getting solid foods at two months old (which was apparently common in the 1970's).  So far, with my older child, he does not appear to have any allergies.  This includes foods that I was allergic to.  I am hoping the same will be the case for my younger son.  Since he is past the six month mark, we will start introducing solid foods to him in a few days.  It will be the beginning of an exciting new chapter for us.  We are keeping our fingers crossed that this may help us get some much needed rest.

So what if you cannot breastfeed?  This something that I know really torment a lot of women.  If you cannot breastfeed, there are different ways to go about getting breastmilk for your child.  Unfortunately, in today's society, many people would opt for formula before exploring some of these alternatives.  However, if you're really determined, I think the following are good choices.  There is wet nursing.  This was something done long ago before the advent of formula and it seems to be enjoying a resurgence in recent years.  There are even websites which show you how to become a wet nurse if you so desire.  Another option is through peer to peer sharing through organizations like human milk 4 human babies.  You can literally look this organization up on facebook in your area to post an ad or look for ads posted by mothers in your area who are looking or willing to donate their breastmilk.  If you want breastmilk that has been tested for diseases (much like blood donations are), then a milk bank is another option.  You can look up a milk bank in your area.  Since this milk is tested and pasteurized, there is usually a fee associated with getting the milk.  In my area, a prescription from a physician is required and it costs $3/ounce (shipping not included).  Since a prescription is required, some insurance companies will pay for the use of banked milk.

It is nice to know that there are alternatives to formula should you choose to preserve the "virgin gut."

Cereal in the Bottle?

I starting hearing about parents putting cereal in their baby's bottle so they can sleep longer through the night.  I don't plan on giving the baby a bottle of anything for a few more weeks to make sure breastfeeding is firmly established.  However, since I am up every 2 hours to nurse, I decided to do a little research to determine if this has been proven to work.

The American Academy of Pediatrics does NOT recommend giving cereal in the bottle until a baby's digestive tract is ready to process solid foods at around 4-6 months of age.  At that time, they should get the cereal from a spoon and not from a bottle.

Prematurely adding cereal to the bottle can cause the baby to aspirate (inhale into their lungs) the cereal and it can also activate any allergies a baby may have.  I have also written a blog post about breastfeeding and foods to avoid which touches on the American Academy of Pediatrics position of no solids before the age of 4 months.  If you're breastfeeding, it should be done exclusively (without solids or formula) for at least 3 months to protect against wheezing early in life.  If you are using formula, then there is evidence that extensively hydrolyzed formula without cereal is best for the prevention of atopic disease (allergic disease).   Adding cereal to the bottle may cause a baby to "overfeed."  "Putting cereal in the bottle is considered by some to be a form of force-feeding that can cause babies to “overdose” on calories."

I don't believe with a lot of things Dr. Sears has to say but he does break it down in an easy to understand manner why you should not feed your baby solids before 4 months.  Aside from the issues mentioned above, he gives an excellent description of the tongue-thrust reflex.  "In the first four months the tongue thrust reflex protects the infant against choking. When any unusual substance is placed on the tongue, it automatically protrudes outward rather than back. Between four and six months this reflex gradually diminishes, giving the glob of cereal a fighting chance of making it from the tongue to the tummy."  My mom fed me solids when I was 2 months old.  She took pictures and at the time said that is what the doctor told her.  You can clearly see that my tongue-thrust reflex was in action at that age.

This is another great post from a pediatrician who advises against cereal in the bottle because of the issues with overfeeding that this may cause.  "A major study looking for the causes of obesity found that short-circuiting young children’s self-regulation of how much they eat is a major cause of later obesity."   "Cereal in the bottle does just that.  Babies that are fed this way may appear to be unaffected – but those few weeks of added convenience may result in a lifetime of struggles with weight. This common practice may have contributed to our being the most obese generation in history.  And it doesn’t even work. Scientists at the Cleveland Clinic studied the effect of cereal on sleep and found that adding the cereal did nothing at all to speed up the age of sleeping through the night. That first uninterrupted 6-hour stretch of sleep came no earlier in those who took cereal early."

After reading more about the issue, I think putting cereal in the bottle is one thing I will not be doing to my baby in the hopes of making him sleep longer during the night.

Is there anything that you should not eat while pregnant or nursing?

This is an interesting question that I have seen pop up quite frequently on some of the pregnancy message boards that I frequent.  According to the American Academy of Pediatrics (AAP) revised policies published in January 2008, "current evidence does not support a major role for maternal dietary restrictions during pregnancy or lactation" for mothers of children that are not at "high risk of developing allergy (ie, infants with at least 1 first-degree relative [parent or sibling] with allergic disease)."

When reading the policy, the AAP defines "atopic disease" as "clinical disease characterized by atopy; typically refers to atopic dermatitis, asthma, allergic rhinitis, and food allergy."

The AAP summarizes their findings based on available data below:

1. At the present time, there is lack of evidence that maternal dietary restrictions during pregnancy play a significant role in the prevention of atopic disease in infants. Similarly, antigen avoidance during lactation does not prevent atopic disease, with the possible exception of atopic eczema, although more data are needed to substantiate this conclusion.
2. For infants at high risk of developing atopic disease, there is evidence that exclusive breastfeeding for at least 4 months compared with feeding intact cow milk protein formula decreases the cumulative incidence of atopic dermatitis and cow milk allergy in the first 2 years of life.
3. There is evidence that exclusive breastfeeding for at least 3 months protects against wheezing in early life. However, in infants at risk of developing atopic disease, the current evidence that exclusive breastfeeding protects against allergic asthma occurring beyond 6 years of age is not convincing.  
4. In studies of infants at high risk of developing atopic disease who are not breastfed exclusively for 4 to 6 months or are formula fed, there is modest evidence that atopic dermatitis may be delayed or prevented by the use of extensively or partially hydrolyzed formulas, compared with cow milk formula, in early childhood. Comparative studies of the various hydrolyzed formulas have also indicated that not all formulas have the same protective benefit. Extensively hydrolyzed formulas may be more effective than partially hydrolyzed in the prevention of atopic disease. In addition, more research is needed to determine whether these benefits extend into late childhood and adolescence. The higher cost of the hydrolyzed formulas must be considered in any decision-making process for their use. To date, the use of amino acid–based formulas for atopy prevention has not been studied.
5. There is no convincing evidence for the use of soy-based infant formula for the purpose of allergy prevention.
6. Although solid foods should not be introduced before 4 to 6 months of age, there is no current convincing evidence that delaying their introduction beyond this period has a significant protective effect on the development of atopic disease regardless of whether infants are fed cow milk protein formula or human milk. This includes delaying the introduction of foods that are considered to be highly allergic, such as fish, eggs, and foods containing peanut protein.
7. For infants after 4 to 6 months of age, there are insufficient data to support a protective effect of any dietary intervention for the development of atopic disease.
8. Additional studies are needed to document the long-term effect of dietary interventions in infancy to prevent atopic disease, especially in children older than 4 years and in adults.
9. This document describes means to prevent or delay atopic diseases through dietary changes. For a child who has developed an atopic disease that may be precipitated or exacerbated by ingested proteins (via human milk, infant formula, or specific complementary foods), treatment may require specific identification and restriction of causal food proteins. This topic was not reviewed in this document.

With this revision, the AAP is stating that unless a child is at high risk for developing an allergy, there is no restriction as to what a mother can eat while pregnant or breastfeeding.  If a child is at high risk, exclusive breastfeeding (with no formula supplementation) for at least 4 months decreases the risk of developing atopic dermatitis (eczema) and an allergy to cow's milk.  For all children, breastfeeding for at least three months may protect against wheezing in early life.  If a child is at high risk for developing an allergy and is not exclusively breastfed, there is some evidence that eczema may be delayed or prevented by using extensively hydrolyzed formulas compared with cow milk formula in early childhood.  There is no evidence for the use of soy-based formula for the purpose of allergy prevention.  Solid foods should not be introduced before 4-6 months of age.  Furthermore, delaying introduction of solid foods after 6 months does not offer more protection against the development of allergies regardless if a baby has been fed formula or breastmilk.  Also, there is no evidence that delaying the introduction of foods such as fish, eggs or peanuts will protect against the development of allergies to those foods.

Pediatric Growth Charts

When I had my first child, I often wondered if he was gaining enough weight.  I breastfed him exclusively and found it difficult to assess if I was producing enough milk for his needs.  Looking at his growth in comparison to standardized growth charts was the only way for me to determine if he was getting enough breastmilk.  My baby was always on the smaller side and that concerned me.  However, as I began researching the topic, I began to realize that the growth charts in use today is very different from the growth charts used several years ago.

Prior to the year 2000, most providers referenced a growth chart from 1977.  The chart developed in 1977 was from a single study whose data was collected from primarily "formula fed, white middle-class infants in a limited geographic area of southwestern Ohio from 1929–75."  This chart was even adopted internationally by the World Health Organization.

The problem with this chart was it tried to compare children from around the world to a select group of people in the United States.  As you know, many people around the world differ in size according to their nutritional status and ethnicity among other factors.  It was this discrepancy that led to the  development of the new guidelines in use today.

In the US, the current growth charts now include a Body Mass Index (BMI) for age charts.  "BMI (wt/ht2) is calculated from weight and height measurements and is used to judge whether an individual's weight is appropriate for their height. BMI is the most commonly used approach to determine if adults are overweight or obese and is also the recommended measure to determine if children are overweight. The new BMI growth charts can be used clinically beginning at 2 years of age, when an accurate stature can be obtained."  The new charts also had a revised head circumference chart which "also show some noticeable differences when compared to the earlier charts. Compared to the original infant charts that were based on primarily formula-fed infants, the revised growth charts for infants contain a better mix of both breast- and formula-fed infants in the U. S. population."

The Centers for Disease Control (CDC) recommends the charts developed by the World Health Organization (WHO) for children 0-2 years old and the CDC growth charts to monitor children 2 and older in the United States.  There are separate charts because the WHO chart only covers children until they are 5 years old.

The WHO standards "establish growth of the breastfed infant as the norm for growth.  The WHO charts reflect growth patterns among children who were predominantly breastfed for at least 4 months and still breastfeeding at 12 months."  "The WHO standards provide a better description of physiological growth in infancy.  Clinicians often use the CDC growth charts as standards on how young children should grow. However the CDC growth charts are references; they identify how typical children in the US did grow during a specific time period. Typical growth patterns may not be ideal growth patterns. The WHO growth charts are standards; they identify how children should grow when provided optimal conditions."  For example, according to the CDC growth chart reference, if a "typical" growth pattern for a particular region is for children to be overweight, it is not an "ideal" growth pattern and children should not be compared to that reference.

"The CDC growth charts are based on primarily formula fed infants.  Only about 50% of infants measured to construct the growth reference charts were ever breastfed.  By 3 months of age, only 33% were breastfed.  In the US, 75% of infants born in 2008 were ever breastfed, 44% were breastfed for at least 6 months and 24% were breastfed at 12 months.  Consequently, the CDC growth charts may not adequately reflect the current growth patterns of infants in the US and they do not reflect a growth pattern typically seen in breastfed infants."

"Growth patterns differ between breastfed and formula-fed infants. Beginning around 3 months of age weight gain is generally lower for breastfed infants than for that of the formula-fed infant.  Linear growth generally follows a similar pattern for both breast- and formula-fed infants.  Formula-fed infants tend to gain weight more rapidly after age 3 months, they may be more likely to cross upward in percentiles on the WHO growth charts, perhaps becoming classified as overweight."

The WHO Standards were developed from data collected from "The WHO Multicentre Growth Reference Study (MGRS)."  "The WHO Multicentre Growth Reference Study (MGRS) was undertaken between 1997 and 2003 to generate new growth curves for assessing the growth and development of infants and young children around the world.  The MGRS collected primary growth data and related information from approximately 8500 children from widely different ethnic backgrounds and cultural settings (Brazil, Ghana, India, Norway, Oman and the USA)."  "The children included in the study were raised in environments that minimized constraints to growth such as poor diets and infection. In addition, their mothers followed health practices such as breastfeeding their children and not smoking during and after pregnancy."

"The MGRS was designed to provide data that describe “how children should grow,” by including in the study’s selection criteria specific health behaviors that are consistent with current health promotion recommendations (e.g., breastfeeding norms, standard pediatric care, non-smoking requirements). This new approach is fundamentally different from that taken by the traditional descriptive references. By adopting a prescriptive approach, the protocol’s design went beyond an update of how children in presumably healthy populations grow at a specific time and place and explicitly recognizes the need for standards (i.e., devices that enable value judgments by incorporating norms or targets in their construction). Arguably, the current obesity epidemic in many developed countries would have been detectable earlier if a prescriptive international standard had been available 20 years ago."  This study "reiterate the fact that child populations grow similarly across the world’s major regions when their needs for health and care are met."

A result of the new standards will be "that stunting (low height for age) will be greater throughout childhood when assessed using the new WHO standards compared to the previous international reference. There will be a substantial increase in underweight rates during the first half of infancy (i.e., 0-6 months) and a decrease thereafter. For wasting (low weight for length/height), the main difference between the new standards and the old reference is during infancy (i.e., up to about 70 cm length) when wasting rates will be substantially higher using the new WHO standards. With respect to overweight, use of the new WHO standards will result in a greater prevalence that will vary by age, sex and nutritional status of the index population."  This is not surprising considering the previous reference was based on "formula fed, white middle-class infants in a limited geographic area of southwestern Ohio."

The new standards establish the following cutoffs:
"Infants and children with a weight-for-length < 2nd percentile are classified as low weight-for-length.
Infants and children with a length-for-age < 2nd percentile are classified as having short stature.
Infants and children with a weight-for-length > 98th percentile are classified as high weight-for-length."

When a child transitions after the age of 2 "from the WHO weight-for-length chart to the CDC BMI-for-age chart may result in a change in a child's percentile classification" because of:

• Changes from one indicator to another indicator.
• Weight-for-length chart to BMI-for-age chart.
• Changes from a recumbent length measurement to a standing height measurement.
• "Standing height measures less than recumbent length. "  
• Changes to a different cutoff value and a different reference population.
• "Breastfed reference population to a primarily formula-fed reference population."

Apparently, many parents do not understand growth charts.  If a doctor is using the CDC growth chart instead of the WHO growth chart, who can blame them?  There was a study published in the journal Pediatrics in October 2009 titled, "Do Parents Understand Growth Charts?  A National Internet Based Survey."  "Understanding a growth chart requires the ability to understand several concepts, including trending over time, proportionality (height compared with weight), and graphical presentation. Health care providers may mistakenly assume that parents understand these concepts."  The study found "the majority of this survey's respondents were not able to comprehend growth chart data fully. The concept of percentile seemed particularly difficult for respondents to understand. Although most reported having heard of the term, many could not identify the percentile of a point shown on a growth chart, and an even larger number could not identify the definition of the term percentile."  "A significant number of respondents were mistakenly concerned about a proportionate child who is smaller (shorter and lighter) than average but growing normally, and they thought that it would be healthier for the child to be at higher percentiles. This confirms the findings of a recent study in which mothers misinterpreted percentile as indicating the percentage of children at that height or weight and thought that growth curves were more satisfactory at higher percentiles. Most respondents expressed concern if a child's growth was shown to measure in the 10th percentile for both height and weight, whereas significantly fewer showed concern about the health of a child who was in the 90th percentile for height and weight. Also, respondents showed much greater concern about a child's absolute weight, compared with a child's height or height/weight proportionality."  The study concluded, "few parents understand growth charts and the implications of the data they present."  The authors recommend, "non–growth chart-based approaches to teaching parents about their children's growth should be considered, because our results reveal that many parents clearly lack knowledge about the growth process and are uncertain about the best ways to assess a child's growth or, indeed, whether tracking a child's growth is even important. For example, our results indicate that parents typically rely on comparisons they make with other children of similar age, rather than growth charts, to judge their child's physical development, which can be deceiving when a large proportion of children in a community are overweight."

The big take home message for me, from all of this, is that if my child is proportionally growing normally (height and weight) and within the 2-98% cutoff, then it is OK.  My child may not necessarily need to be in the higher percentiles to be considered "healthy."  Also, I need to make sure my provider is using the WHO standards when evaluating my breastfed infant as opposed to the CDC references which show typical growth patterns that might not be ideal growth patterns.

Here are the links to the WHO Growth Charts:
Birth to 24 months: Boys Weight-for-length percentiles and Head circumference-for-age percentiles
Birth to 24 months: Boys Length-for-age percentiles and Weight-for-age percentiles
Birth to 24 months: Girls Weight-for-length percentiles and Head circumference-for-age percentiles
Birth to 24 months: Girls Length-for-age percentiles and Weight-for-age percentiles

Formula Feeding Does Not Equate with Improved Sleep

As you have probably already guessed from my previous posts about breastfeeding, I am a big supporter of breastfeeding.  I think I have heard everything when it comes to why I should stop breastfeeding and switch to formula.  My child is too old, formula is more convenient and feeding formula will let you have more sleep.  I stumbled across an interesting study published in the journal Pediatrics.  The purpose of the study, "Infant Feeding Methods and Maternal Sleep and Daytime Functioning,"was to explore maternal actigraphically measured sleep, subjective sleep reports, and daytime functioning on the basis of current feeding method status during postpartum weeks 2 through 12."

The study "did not find differences between women who were exclusively breastfeeding, exclusively formula feeding, or using a combination of the 2 methods, with respect to the assessed parameters."  "The contrast between our negative subjective maternal sleep findings and previous studies that showed that mothers reported that their breastfed infants awakened more often at night are intriguing. Without our and others’ evidence, it would stand to reason that, if the infants awakened more often, their mothers would too. It is possible that, despite their self-reports, breastfeeding mothers are awakening more often during the night to feed their infants but they return to sleep more quickly or sleep during feedings and consequently do not remember those awakenings."  The authors "suggest that, if breastfeeding mothers are awakening more often at night, then breastfeeding itself may have a compensatory effect. In other words, breastfeeding mothers awakening more often at night may return to sleep more quickly and not remember these awakenings. Possible reasons for this may include the fact that they are not exposed to as much ambient light or physical activity, compared with preparing formula. It also is possible that breastfeeding mothers sleep during feedings."  "4 nucleotides present in breast milk have strong maternal circadian rhythms and seem to facilitate a “hypnotic action” in infants. In addition, differences in circulating prolactin levels are suspected to have a primary role in sleep architecture differences among breastfeeding and formula-feeding mothers. Prolactin shows a nocturnal peak, which is vital for milk production, and usually is associated with facilitation of sleep onset and delta wave activity important for restorative sleep."

The authors concluded "to date, there is little evidence to support the notion that breastfeeding has a negative impact on maternal sleep.  Women should be told that a choice to formula feed does not necessarily equate with improved sleep. The risks of not breastfeeding should be weighed against the cumulative lack of evidence showing any benefit of formula feeding on maternal sleep."

I find the discussion of the study findings very intriguing.  Unfortunately, the study only had 24 participants in the first phase and 70 in second phase.  This is not a large sample size and undoubtedly the formula supporters will point to that as an argument to invalidate the study.  Despite the small sample size, I still find the notion that formula feeding will not necessarily allow a mother to get more sleep to be true.  I'm a horrible insomniac and if I had to wake up to prepare a bottle and then feed a bottle, I would find it difficult to return to sleep.  If I am breastfeeding, I can get the baby, nurse the baby and fall back asleep all without having to turn on the lights or going far from my bed.  It is just one more thing I can present to those who have tried to discourage me from breastfeeding.