My first trimester I was very exhausted, second trimester I started commuting if I ate large meals (only lasted for the first four weeks) but otherwise felt great, happy excited, loved my growing belly and the baby it contained. At the third trimester, halfway through week 27 I was exhausted again. As a FTI I thought this was normal. I was caring around more weight which would naturally make me more tired right? Anyone who had kids that I mentioned this to agreed and stated it was only going to get worse. So I didn't worry about it -shrug- . When I went for my gestational diabetes testing it turns out my iron was low, I was anemic, and that's why I had been feeling so tired, run down, couldn't concentrate for very long. I started taking iron supplements as per my midwife and after only a few days I feel great again!