I've been taking extra magnesium (500 mg) every other day for constipation, and have been trying to get information about if it's harmful during pregnancy. I haven't really been able to find out one way or another. Most places say that the limit for magnesium during pregnancy is 370mg. My prenatal has 200mg (and I'm sure I get some from foods). The only thing I've been able to find are sites that say magnesium can be toxic if you have too much, although other places say that Milk of Magnesia is safe to take for constipation during pregnancy, the active ingredient of which is magnesium. So I'm at a loss, because I don't see how some places can say it's harmful to go over the recommended dose when others say that pregnant women can take Milk of Magnesia every day for constipation.