This is a little of a tangent, but it does have to do with Sun's pregnancy. Juliet told Sun that on-island males' sperm counts were 5 to 6 times higher, but that is presumably for normally fertile off-island males. Since Jin was infertile before coming to the island, maybe his count is simply normal on the island, and somehow that will make a difference in Sun's ablility to carry the baby to term.

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