magnesium gluconate 500 mg 120 capsules

so I looked up some information here-->  http://www.webmd.com/vitamins-supplements/ingredientmono-998-MAGNESIUM.aspx?activeIngredientId=998&activeIngredientName=MAGNESIUM

I didnt find much so I guess my question after reading everywhere that the side effects are inconclusive as far as how it effects a fetus, so my question for the seasoned mothers who have used this exact type personally, I want to know were your children healthy and did you need to be induced? Also what was your personal experience like? I have been perscribed this to prevent contractions, I am 27w with twin boys, am taking weekly progesterone and today I finished my second shot of my first and last round of beta to mature the lungs.