Pregnant and laxatives ?

Has anyone taken magnesium citrate and pregnant? I’m 12 weeks with a headache for 3 days now and I know it’s bc of the iron in the prenatals. My stomach always feels rock solid and I don’t go to the bathroom the way I used to b4 becoming pregnant. TMI sorry. But. It’s Friday and the doctors office is closed for the weekend. They recommended miralax and it did nothing. I have taken mag citrate in the past and it is the best, cleans you out completely. Google says it’s safe, but I wanted to see if any preggies have taken it pregnant without any complications.

Thanks!