Really did you not read what I actually put saying I didn't believe it myself? Really, I mean come on at least read the post before answering.
Bruiser, while I tend to believe that Lyanna died during or as a result of childbirth, in fairness to you, you are right that there are alternatives that would work. Consider:
Robert dies in a room that smells of smoke, blood and death. Cause of death: gored by boar.
Lyanna dies in a room that smells of blood and roses. Cause of death: infection (she had a fever).
So we have two people dying in rooms that smell of blood, and we know for sure in the case of Robert that he was never pregnant.
Now, there are any number of ways a person could acquire and die from an infection. The only thing Ned does not ever think about is the cause of the infection.
On the bed of blood, aside from Robert's death, there are three references I can recall to blood and beds: flowering (Sansa), maiden's blood (Lady Dustin) and childbirth (Dany).
Bloody bed, as used by MMD, almost certainly refers to childbirth. Bed of blood, or beds of blood -- the other two phrases -- might refer to childbirth, they might refer to one of the other options, or they might refer to all three.
Finally, we know that giving a person the gift of mercy would produce a lot of blood. It would also explain why Lyanna's fear went away when Ned made his promise, if Ned's promise was to provide her with the gift of mercy.
As I said, I think Lyanna gave birth and died as a result, in part because I think the bed of blood and the cause of the infection are connected. But there are other possibilities that could work.