This is from a study published in 2000, so it's not exactly new news, but I just found this article saying that most residents (doctors in training) don't know that breastfed babies follow a different growth curve than formula fed babies, and that it's normal for a bf baby to slow way down in growth right around 4 months.  So - if your doctor mentions that your baby should be eating more because they're grwoing too slowly and is pushing supplementing, be sure to ask if they're familiar with normal breastfed baby growth rates.  Note that even among physicians with some personal breastfed experience, 88% didn't know about the growth curves. Here's the abstract from the paper:

Resident Physicians' Knowledge of Breastfeeding and Infant Growth

Jeanne-Marie Guise, MD, MPH, and Gary Freed, MD, MPH

Background:It is well documented that breastfed infants grow differently from formula-fed infants. The purpose of this study was to assess resident physicians' knowledge of breastfeeding and infant growth. Methods:A cross-sectional, self-administered survey was administered to family medicine and pediatric resident physicians from three large, hospital-based public and private programs in North Carolina. Results:One hundred and seven (46%) of 235 residents completed the study, representing 55 percent of family medicine residents and 39 percent of pediatric residents. Ninety-nine percent of participants reported frequently or always plotting infant growth at well-child visits. None reported plotting breastfed babies on a chart specific to breastfeeding. Only 5 percent of participants knew that breastfed infants grew at a slower velocity than formula-fed infants after 4 months of age. This knowledge was not significantly related to specialty, year of training, or gender; it was significantly related to breastfeeding experience (p < 0.04). Of the residents who did not have personal experience with breastfeeding, 99 percent answered incorrectly compared with 88 percent of those who had some personal experience in breastfeeding. Conclusions:In this sample of family medicine and pediatric residents, almost all were unaware that breastfed infants grow at slower rates after 4 months of age. Since the frequency of breastfeeding is increasing in the United States, it is important that physicians be able to monitor the growth of breastfed infants accurately and provide expert counseling for breastfeeding mothers.   To see the charts for breastfed babies,  Here's a link: http://www.kellymom.com/babyconcerns/growth/growthcharts.html  - this site on kellymom.com shows a couple of charts - the first is a standard growth chart with typical breastfed babies plotted as red dots to show the difference in the curves (only 50th %ile is shown for bf babies).  This is from the CDC, but they apparently haven't completed the new charts for exclusively bf babies yet.  the other two charts are WHO charts for exclusively breastfed babies for 12 months - but since they are from WHO they don't necessarily reflect US populations.  If you run into a ped telling you to supplement a bf baby who is "falling off their curve", I recommend printing out the first chart to take with you.  it's directly linked here: http://www.kellymom.com/babyconcerns/growth/chart1.html This link: http://www.cdc.gov/nccdphp/dnpa/growthcharts/training/modules/module2/text/module2print.pdf is to a CDC document on growth curves - the breastfed baby information is on page 12.