My daughter (born on 02/13/08) weighed 3780 grams at birth. She lost during her first week, and reached a low point of 3416 grams on 02/17/08. From then she has been gaining, however the weight gain has been slow (according to my breastfeeding clinic). Her last weight on 05/11/08 was 5023grams. Therefore, we have had a total weight gain of 1607 grams (if you look at the lowest weight she reached). For the past 3 months, I have visited the breastfeeding clinic almost weekly as my family doc, and the clinic both have been concerned about the weight gain. They have suggested a milk supply issue (I am sure it's not milk supply-have no problem expresssing etc.), and are at the point where they keep "threatening" formula if she doesn't "gain appropriately" on these weekly weigh-ins (they are looking for a 15-30gram/day gain). Her wet/dirty are great (at least 8 HEAVY wet, and 2-3 dirty/day), and she is meeting all developmental milestones. On the WHO breastfeeding growth chart, she falls somewhere around the 40th percentile. My question is this: do you calculate weight gain based on their lowest weight they reached, or by birth weight?