You know what I think, from previous posts. Many on this royal line had porphyria. Charlotte's death may have been brought about by the doctor treating her wrong for a porphyria patient. The strict diet contributed. Then the alcohol during her long delivery. I forget what drugs she had during delivery, if any, which were very likely to have triggered porphyria too. But the doctor's ignorance on this subject really was not his sole fault. The whole medical profession was grossly ignorant of what triggers porphyria attacks, what makes a porphyria patient sicker in a situation like pregnancy and delivery. With proper modern knowledge (which admittedly is hard to find, but perhaps not hard for the royals to find it they need it) Charlotte almost certainly could have had a successful pregnancy and delivery. It was possibly ignorance that killed her, but the ignorance was not unique to her physician.
50% of children of porphyria patients have porphyria. 75% of children whose parents BOTH have porphyria have the tendency. It sometimes does not show itself if it is not triggered. Diet, drugs, and alcohol are all important triggers.
Charlotte's apparent good health before pregnancy is quite common among people who have porphyria, if they have not been triggered into active illness. Charlotte's austere diet was probably the first big trigger.
That's what I think and I know not everyone will agree.
You're making a few huge errors here.
First of all, your statistics are being misrepresented. If a trait is determined by one gene (G being the dominant and g being the recessive) and a person has parents who are Gg (having it) and gg (not having it) then they have a 50% change of displaying the trait; however if the parents are GG and gg then there is a 100% chance of the child having the trait. Similarly, if both parents are Gg then there is a 75% chance of a child having it, but if one is GG and the other Gg (or both are GG) there is a 100% chance of the child displaying it. However, these statistics are
for each individual child; if a Gg and gg couple have 4 children, probability says that 2 of their children will be Gg and 2 will be gg, (if the couple is Gg and Gg then 1 child will be GG, 2 Gg, and 1 gg), but it is entirely possible for other outcomes to happen. While the probability may say one thing, the actual outcome may be entirely different. The genes aren't going "oh, well, the last 2 kids didn't display the trait, so this one needs to." The slate is wiped clean each time.
Therefore, assuming that George III had porphyria and was Gg for it, then each of his children had a 50% chance of getting it. That does not mean that 50% of his children had it, just that they had the chance of having it. Hemophilia is similar, and we can see how that works in Queen Victoria's sons - as Victoria was a carrier and the trait is passed on using the X chromosome it means that each of her sons had a 50% chance of getting the disease - so, according to probability, of her 4 sons, 2 of them should have had hemophilia. Except, only one of her sons had it. Probability isn't always what happens.
Secondly, and this is the biggie to me, it's not actually 100% that George III himself had porphyria, let alone any of his children or grandchildren. There was a hypothesis postulated in 1966 that George III's madness was caused by porphyria. The idea has gained a lot of popularity causing people to beleive that he did in fact have porphyria, but it's still just one theory about the cause of his madness, and not one that's always accepted as valid by historians and psychiatrists. Recently it's been argued that the claim is based on a very selective reading of the sources - as if the people who put the claim forward only looked at evidence that would support their claim.
Now, regardless of whether or not her grandfather did in fact have porphyria it's entirely possible that Charlotte had it... although there doesn't seem to be much evidence of it. Further, the account of her labour is enough to suggest that it really was just the labour that killed her - she went into labour on the 3rd, and didn't deliver until the 5th. Even a less problematic labour would have had a chance of killing her in those days. If memory serves, she hemorrhaged after the birth and they couldn't get the bleeding to stop - which is to this day still a serious threat to women when they give birth and can often require blood transfusions (which they wouldn't have had at the time). Saying that Charlotte died of anything other than complications due to labour is a stretch.