Magnesium?

I have have been admitted to the hospital for having high blood pressure. The doctors are still trying to figure out why my blood pressure is fluctuating so much. One minute it's perfect and the next it's sky high. This is the second time since Tuesday of last week! I'm only 25 weeks. They have already given me 2 steroid shots to mature his lungs. Now we are receiving a magnesium drip. Has anyone else been through this? What happened after you received it?