Iron supplement

I’m 31 weeks pregnant now. I haven’t been taking iron supplement. However, I just did a blood test recently, and the results came back showing that I’m low in iron. My next doctor appointment will be in a month time. I think it’s better to start taking iron supplement asap as I read that iron is very important for baby growth. So I would like to check, which iron supplement (what brand) that y’all are taking? Please recommend! Thank you so much