Being told that your baby is too small or too big? Make sure you're using the new growth charts.

I've gotten several questions from readers recently about the new WHO growth charts. 

But before I talk about the new growth charts I have to say that if your baby is not gaining well - especially in the early days and weeks - it's important to consult with your pediatrician (and probably a lactation consultant) for care suited to your situation.

So, what if your 5 month old breastfed baby is falling off the growth curve, and your doctor is starting to talk about supplementing with formula?  The first thing to do is check that your doctor is using the new WHO growth charts.

A little background:  Until recently the growth charts used by pediatricians were based on a sample of all formula-fed, all Caucasian babies born between 1929 and 1975 in Ohio.  These babies also often started solid foods before four months.  I recently learned that these charts were used around the world to chart babies' growth.  More recently, in 2000, the CDC released a chart using a mixed sample of breastfed and formula-fed infants.  It yielded similar problems (explained below).

Research from the early 1990's demonstrated that breastfed and formula-fed babies have different growth patterns.  The most significant differences are that breastfed babies grow faster than formula-fed babies in the first few months, and then "lean out" compared to formula-fed babies between 3 and 12 months. 

So, if you try to chart a breastfed baby's growth using the formula-fed charts, you might see a baby who is falling off of the curve after the first 2 months.  This sometimes resulted in recommendations that mothers supplement with formula.  It also meant that formula-fed babies who were experiencing excessive weight gain in later months - and at risk of later overweight and obesity - were viewed as normal and no interventions were recommended. 

The new WHO charts, released just last year, use a sample of nearly 9,000 babies who were exclusively breastfed for the first six months.  The study methodology is described in detail here.  To me, the most interesting finding is that, when factors like malnutrition, socio-economic status, and maternal smoking are controlled for, growth of children around the world is quite similar.

The WHO is clear that these charts are not intended to apply just to breastfed babies.  They can serve as an important early warning to doctors if a formula-fed baby is experiencing excessive weight gain - a particular concern because formula-fed babies are at risk for overweight and obesity.  The WHO states, "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."

Here are links to the new WHO charts:

• Chart for girls, birth to two years, showing percentiles (pdf)
• Chart for boys, birth to two years, showing percentiles (pdf)
• A calculator for converting pounds to kilos, which you'll need to use the charts.  Remember to first convert ounces to fractions of a pound - i.e. 6 lbs 8 oz = 6.5 lbs.
• Other charts, including height for age and body mass index for age
• Frequently asked questions about the new charts (particularly helpful if your pediatrician has questions)
• A video on the development of the new growth charts
• Software your pediatrician can use to implement the new charts

When my son was born in 2003 the best charts available were from the CDC, and they reflected a mixed sample of breastfed and formula-fed babies.  True to form, he appeared to be growing excessively in the first few months, and then seemed to be slipping off of the curve as he neared 6 months.  I now know that this is a normal growth pattern for a breastfed baby.  I recently found his growth chart and realized that it had formula company logos running down the side!

I think that this is such an important development that I made it part of the Motherwear Pledge.  So, the next time you have an appointment with your pediatrician, ask if he or she is using the new charts.  Then, record your action in our pledge poll!

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