First of all, what growth chart is your doctor using? A disturbing number of docs use CDC growth charts, in part because the electronic medical record might only have the CDC growth charts convienient for them to plug numbers into. However, as the CDC web sites itself states: "In the United States, the WHO growth standard charts are recommended to use with both breastfed and formula fed infants and children from birth to 2 years of age (CDC, 2010)." I'm not sure why the CDC growth charts still even exist. They were created based on a fairly small number of very similar children (white, formula fed, living in one region in the US), and tend to make especially breastfeed babies look like they are not growing well. How stressful for parents!
So before you start stressing about how your baby is growing, make sure that the tool you are using (the growth chart) is accurate! I like to keep track of my children's growth curves on my own app, since I'm obsessive like that. I use Growth on ipad. For doctors who don't know about the CDC to WHO growth chart switch (I know, how is it possible that a doc doesn't know that??? sigh), this app has a nice function where I can flip between WHO and CDC growth charts to do a little education for the doc. "See how my baby looks like she's dying on one chart, but fine on the other? Yea, guess which one is actually accurate..."
Now that we are sure we are looking at accurate information, what do the percentile lines mean? Those lines follow the average growth curves of average babies. So the most babies follow somewhere around the 50th percentile line. An equal number of babies should follow the 75th percentile line and the 25th percentile lines, and they are still normal growth patterns; those babies just have more chubbiness or thinness, tallness or shortness, in their genes for that period of life. The numbers don't seem to dictate whether the child will be tall or short, and especially not overweight or thin, as adults. The numbers are mostly used just to make sure a child 'picks a line and sticks with it.' Basically, it doesn't matter which percentile line your kiddo is on (so stop gloating, you 90th percentilers!), as long as they stay roughly with that line! Deviating sharply up or down is an indication that something isn't right with how your child is growing, and should look into it more.
So will LPLD affect how your child grows? Hopefully not. Following a child with LPLD's growth percentile line can definitely help reassure you that, despite not getting much fat in their diet, they are still growing appropriately.
Which is nice to hear/read, but hard to take to heart as a parent when you are so worried about your little one.
But in case it helps reassure you, here are my children's weight growth charts. Mostly this is pertinent to compare my kids with LPLD (Teresa and Monica) vs Mary, who got to eat as a baby (and continues to eat to this day) all the ice cream, cheese, and avocado she could want!
|Teresa's age vs weight|
|Mary's age vs weight (no LPLD)|
|Monica's age vs weight|
Even though I didn't know it, I just have rather small children it seems! Nothing to do with LPLD. There was no extreme dip when Monica was diagnosed at around 18 months to two years and we changed her diet drastically. There was no dip when Teresa was diagnosed at 6 months and I switched her to skim breastmilk.
In summary, trust your parental instincts, as well as your child's ability to tell you when they are full. It's hard not to worry about whether your LPLD child is getting enough to eat, I am right there with you. I might well be pulling up this post in the future when I am anxious myself!