Dear all: This is a topic that periodically crops up and about which Kathy Dettwyler used to respond frequently. Since she has not been participating on Lactnet for a while, I thought I'd make some comments now. My background is in nutritional epidemiology and one of my professors was actually a physical anthropologist, well versed in anthropometry. Having worked in developing countries, growth monitoring was a huge part of nutrition interventions. I also worked with some of the folks at CDC who developed the new growth charts - so I know how tricky and onerous the statistics are for developing growth charts. It is not by any means and easy job to develop these. So, lets go over a few items that have been discussed. 1) Weights and lengths were lower in the past. Much of the lower weights and lengths for infants and chilren under five several generations ago were due to malnutrition, as are the differences seen between developing countries and developed countries. The genetic differences between populations living in different countries is also actually quite minimal. Both of these observations are well-documented in the scientific literature. When looking at "healthy" well-nourished children in the past and in various different countries, one sees surprisingly little difference in growth rates. Even well-nourished pygmy children grow at about the same rates as other populations during the 0-5 year old age range. About the only population where the literature suggests that there may be some slight differences are the South East Asian populations and that difference is minimal - about 1 cm. (Reynaldo Martorell has done a lot of work on this issue if you care to do a literature search). What we are seeing in the most recent period is a rapid increase in UNHEALTHY growth - i.e. obesity I want to make it very clear that while genetics does not play much of a role in differences between populations, it may very well play a strong role in individual families. So those of you who have families that tend to be large and those of you who have families that tend to be small - it is most likely genetics. 2) The old charts are only based on bottle fed infants. This is actually false. The old charts were based on a population of infants who were fed by mixed feeding methods. What this means in terms of the growth charts is that the SPREAD of growth may possibly be wider than it should be, because of the "unhealthy" extra weight gained by formula fed infants during the 4- 6 month period. 3) The old charts are not useful because bottle fed children are included. This again, is not true. The charts have been used in many nutrition programs in developing countries with success. The charts are only useful if you look at the tragetory of growth, not the percentiles. One looks for sharp dips in growth. AND since it is well known that the weight gain of "healthy" breastfed infants tends to be lower in the 4-6 month period - a slight downshift in the percentiles is expected. Slight deviations are not of concern. A drop of 2 z-scores, which I have never heard used in pediatricians offices or on LACTNET, but are widely used in developing countries, is what usually triggers looking at a child's situation more closely. 4) The new growth charts on breastfed infants will solve all our problems. This is where I have to pipe up with what Kathy Dettwyler has mentioned before on LACTNET. The new charts are based on US moms - who do not often practice breastfeeding the way that it is practiced in developing countries. We schedule, we train infants to sleep through the night, we have them sleeping in cribs. This may very well play a role in reducing the upper end of the curves on the breastfed charts. Furthermore, these are the women who succeeded. In our US society, there is pressure to supplement slow gaining infants with formula. Some of these infants actually may have been exhibiting normal healthy growth for their physiology. These infants would have been eliminated from these charts. So - this may have reduced the lower end of the curves on the breastfed charts. Finally, none of this is relevant anyway if one simply monitors the growth tradgetory AND the infants health and behavior. Growth alone is only one piece of the pictures. Susan E. Burger, MHS, PhD, IBCLC *********************************************** To temporarily stop your subscription: set lactnet nomail To start it again: set lactnet mail (or digest) To unsubscribe: unsubscribe lactnet All commands go to [log in to unmask] The LACTNET mailing list is powered by L-Soft's renowned LISTSERV(R) list management software together with L-Soft's LSMTP(R) mailer for lightning fast mail delivery. For more information, go to: http://www.lsoft.com/LISTSERV-powered.html