"More likely than not" is already an uncertainty. There's no need to qualify it with further uncertainty. I'm working with the same information you are. All we

"More likely than not" is already an uncertainty. There's no need to qualify it with further uncertainty. I'm working with the same information you are. All we know is that it was 28 weeks. That gives it a > 50% survival chance if delivered in a hospital in the US. You might come to a different number if you used different sources, or if you had more information. But "we can't know for certain" is just a truism; nobody's saying we know anything for certain. We're just estimating the probability based on what we do know.