I'm nearly 38 weeks and atm have the windows open all day and then the fan on when we go to bed - however, DD2 threw a spanner in the works Wednesday night by getting in with us (she was poorly) and had to turn the fan off because it was disturbing her. I actually had sweat dripping down my chest, in the creases of my arms etc
I really feel for you ladies...try a hot water bottle filled with cold water or one that's been in the fridge/freezer, either put your feet on it or slip it into a pillow case or wrap in a towel and put in your pillow...or have you heard of a 'chillow'??
I was pregnant in the summer of 2006 - it was a belter summer but not when you're cooking another human! I found a chillow really helped but there's nothing better than good ole air con
Failing that then the freezer section at the supermarket also helped - esp now most are open 24hrs