Sorry, I don't mean that it doesn't make a huge difference if he were say a newborn, it would be huge, a 5lb newborn often has trouble latching, staying awake to nurse, is often more prone to illness/infection, may have respiratory issues and a plethora of other things. He/she may also be perfectly healthy. Some people have full term tiny babies, some people have full term huge ones.
What I meant by it not making a huge difference is in the fact that by his age (4 months) he should have been nearly double his birth weight. Based on his hospital photos, I would say he was at least a 7lb pound newborn, because he is very filled out, and generally speaking, smaller babies aren't as filled out and appear to be "skinny" until they put on a couple of pounds. Especially in their faces and necks. Not always of course, but just a generalization. SO, for a 4 month old, being at or below his birth weight is beyond heinous, regardless of whether he was 7lbs or 5lbs at the time of his death. A baby is expected to lose a few ounces after birth, but generally they are back up to birth weight within 2 weeks, if not sooner. So, assuming he "thrived" for the first 3 or so months of his life, or even the first 7 weeks, he really had to have gone through pain of starving and dehydration and of course further discomfort and lethargy etc as his organs began to shut down, until his heart ceased to beat.
One doesn't have to lose much weight at all to starve to death, but if he had grown properly up until the past week of life (which I personally doubt), he should have been around 14lbs (give or take), meaning he would have lost about 50% of his body weight had he followed a normal growth curve, and if he didn't grow, then he spent months in some form of starvation, basically forcing him to stay small.
Whatever the case, a part of me hopes that they did drug him and that he didn't "feel" the pain his body would have gone through. At least it would have been slightly more humane if he would have been in a sedated state. I realize I haven't seen anything saying this, and I feel horrible for even thinking it would have been better for him
All of this is JMO based on the approx growth link I posted upthread.