I found the exhaustion to be massive this pregnancy for the 1st trimester. It stopped with the ms at 12wks though. If you are exhausted to almost a debilitating point i would speak to a dr about it and get your iron levels checked. My iron levels dropped at about 28wks this time and when they were low i was exhausted, ive since had an iron infusion and i feel more energy again, so it might be something like that for you.