During pregnancy, the white blood cell count is slightly elevatedhalf of the fetus is Mom, half is Dad, the body sees unfamiliar DNA and raises its guard. "Normally, the moms immune system is kept in check, and thats why the baby is accepted" says Dr. Michael Cackovic, an instructor in the department of Maternal-Fetal Medicine at Yale University.
In Lost it is stated that the mothers have a low white blood cell count and the immune system turns on the baby. Whenever anybody has a low white blood cell count theyre at risk for infection. So if a mothers immunoresponse dropped quickly, she would become more susceptible to any kind of external invasion. And what can cause a reduced white blood cell count? You guessed it: electromagnetic radiation.
Radiation kills any cells that are rapidly turning over, that are rapidly growing., Cackovic says. So, yes, the low white blood cell count can definitely have to do with the islands electromagnetic radiation. And its logical to say that it can also be why Roses cancer went into remission.
-- Popular Mechanics
I am perfectly happy with that explanation. The radiation from the incident lowers the white blood count, compromising the immune system forcing the body the fight off the foreign tissue -- the baby -- and leaving the mother open to infection. With the radiation killing any rapidly growing cells, it essentially acts like chemotherapy too.