Has anyone used magnesium sulfate

Last year my pregnancy ended in a miscarriage at 15 weeks. I am pregnant again almost 16 weeks. I also recently found a SCH, which scares me badly, being that was a huge part of why I miscarried last year. Anyways with all of that being said, now when I get any type of cramp or pains it scares me. Has anyone had a similar situation and used magnesium sulfate just in case or your doctor strongly recommended it? Just curious about anyone else's experience with magnesium sulfate.