I was told by woman in boots when I was looking for magnesium that I would be better off just taking a multivitamin pregnancy supplement as it had the recommended doses for everything inc magnesium x
Your supplement has 384mg of magnesium. I would be happy to take that dose during pregnancy 🙂 Magnesium is very safe, you can read more in this published study https://pmc.ncbi.nlm.nih.gov/articles/PMC7558284/
Is this a prescription from GP or over the counter supplement? That’s quite a high dose? Should be no more than 400 mg daily. I personally avoided magnesium supplements (was recommended it to help with sleeping) and made sure had plenty of magnesium in diet. If in doubt I would check with your GP.