I don't mean an unattractive hairstyle 
I'm 19 weeks and for the last week or so I've felt like I'm in a mental fog. When I'm working my brain feels 'fuzzy', like it's hard to think straight. I'm forgetting things, taking ages to complete tasks and generally feel very 'slow'. I'm in a professional career where I am expected to be very decisive and proactive at all times. I got a minor bollocking about being a day late with something (I had explained I couldn't get it done in time and it actually wasn't critical, but I've never missed a deadline before). No allowance is made for pregnancy whatsoever (I'm not complaining about that, I just know some workplaces are a little bit more 'adaptive' to visibly pregnant women).
This is my second pregnancy, and I don't remember being like this until much closer to the end when I was absolutely shattered. I'm wondering if this mental fog could be a symptom of low iron? Anyone else had this and found a cure?? Not sure I can do another four months like this!