The theory that I have that always fits is the alternate reality theory. The Losties are not in their correct dimension. Oceanic 815 that was found, per Naomi, was really found in my opinion.
All dimensions are slightly different from the others. That's why the flash forward was interesting... they have to slip into their lives again that are slightly different than they actually lived in their own reality.
Kate's "new" reality is great, she obviously isn't being chased by the Feds. She looks like she's doing well. Jack on the other hand is not adjusting to his new reality well at all... he wants to go back. The fact that Jack referenced his father still being alive shows that some things are different. So everyone is living in an alternate reality and all pathways lead to the island somehow.
Everyone kept calling Jack a Hero... "Hero" of what... it wasn't the car accident... whatever Jack did to be a hero, he didn't do in his reality... maybe being this "hero" is more than he can handle.
It's also creepy how Oceanic still exists, because in our reality with the web sites and such, they've gone bankrupt, but Jack referenced that they were all given unlimited fights and he gets on a plane every weekend hoping to crash on the island. Seriously... that's insane.
And what if Locke is not the right Locke from the other Losties reality.... maybe this Locke never was in a wheelchair, but maybe mind and matter got mixed up and it's one Locke's mind in another Locke's uninjured body.
What if Rose's cancer really wasn't healed... but it's another Rose altogether.
What if the other Jin was sterile, but this one's not?
Remember during Bernard and Rose's flashback early this season or last... they were arguing about some event (anniversary or something...) that they remembered details differently... maybe they remember correctly for their reality.
Where the dimensions meet, everything, perhaps, got mixed up...maybe everyone is from a different reality.
Jacob maybe out of phase, out of time, something to which Ben is attuned.
I think it will be something similar to this theory that will be able to justify any situation that has been presented to us in LOST. For example, the numbers 4, 8, 15, 16, 23, & 42 only significant because they've shown up most in most realities. The numbers themselves aren't really that special, but if you could look at all realities at once and see that those numbers show up in the majority of them... then the island, a place there realties meet, would predominantly consist of those numbers. If you notice, not every single number in the show has been one of the numbers... but most have.
Maybe women that get pregnant on the island die because if all realties converge on that island then energy and matter converge there also making the fetus (from each and every reality) unstable or overwhelming to the mother. But people that were already pregnant were okay because each "spirit", child, "fetus", "life-force" (whatever you wanted to call it) were already out and dispersed into their own realities, therefore not being "too much" for any one person to handle... (i.e. the pregnant women)
You see... it can all be explained away with alternate realities.
Theory by Joseph
