My midwife has suggested yoga squats to keep my little girl's head lower down in the pelvis (she likes to flip). Maybe these would help you too? I would just be careful with the positions--get a good book, tape, or instructor to show you so you don't injure yourself. Also be very sure she is head down first. They are relatively easy to do and always make my hips and back feel great. At 40 weeks it may be a good idea to do them next to a sturdy chair so that you can hold on for balance.

Good luck.