This message is to the two moms who are nursing their babies, but the babies are starting to fall off the growth charts. It is also to any moms who have a skinny baby, failure to thrive, etc. Also, for those vegetarian/vegan moms, or those on restricted diets due to food allergies (I know about this all too well) ....
Please have your baby's MMA (methylmalonic acid) levels checked. This is a blood or urine (urine tends to be more concentrated, perhaps more accurate) test that can see if B-12 is working correctly. B-12 levels themselves can be normal or even high, but they are fictitious (as I was told by Sally Pacholok, R.N., author of the book "Could it be B-12?").
B-12 deficiency (or B-12 that isn't working in the body) can cause mental retardation, neurological problems among other things - but most/all of this is reversible if caught quickly enough and treated with simple vitamin therapy.
B-12 is found in beef and dairy, so if you are a vegetarian/vegan for personal or food-allergy reasons, or if you have asymptomatic pernicious anemia you could be passing on B-12 deficiency to your baby, or your baby might have something wrong and B-12 doesn't work correctly in their body.
My son has stopped gaining weight, and I thought it was because I was too stressed to produce much milk, or not feedign him enough solids. His head circumference is staying the same size, so it is slipping on the growth charts ... We had his urine MMA checked and it was high. We had it done again, and it was still high, even though his serum B-12 is normal (this is just to say, the B-12 level can be in the normal range, and the baby not be anemic (CBC hemoglobin higher than 10.5), but if B12 is not working in the body then MMA levels start to shoot up and there is a problem). We are seeing a gastroenterologist and a hemotologist.
Here's something to read (just for information)
It's probably not a bad idea to have it checked.
Hope this is helpful,
Kelly (mom of Ashley, Dylan, and Jack)