don't know I thought they were concerned about low iodine levels these days contributed in part by our lack of salt in cooking etc (and the fact that when we do we use non iodised salt) and these affects on pregnancy. The only other think I could think of is too much salt and not enough water and some element of dehydration (total guess by the way) - will be interested to hear cause salty foods is about all I can stomach for the morning sickness stage.