Except, at that age, in most first world or even second world countries a girl that young isn't going to be expected to delivery naturally, and the medical care would push the risks to the girl into at least single digit mortality, if not below. The youngest girl to have a baby was delivered by c-section, in the nineteen THIRTIES, and went on to get married and have more children once she reached adulthood. Medical science has progressed to the point that tiny dwarfs and paraplegics and literal 70 year old grannies can carry babies to viability.
If you're going to argue that preteens should get abortions, you can't use the argument that it's because carrying the baby to term will kill them. You've got to pick a different angle of attack.