Answer from Kerryn - It's true, most women get some degree of back ache in pregnancy.
It's incredible how much the female body changes, and hey, when you're carrying a watermelon in your belly it certainly doesn't help with back pain!
Length is key. And by this I mean lengthen from tailbone to spine.
So your posture is really important. Try not to slouch, it won't help your back, it will just make it worse. This goes for when you sit and stand and walk.
You don't want to fatigue the muscles, you just want enough to get the blood pumping and those feel good endorphins to hit in.
So in third trimester getting out for a few shorter walks is probably going to be better than trying to do one big one.
The Prenatal Pilates routines I have in third trimester really focus on back strength and glute strength, which help with back strength and care, so keep up the Pilates!
And try out my Bed time routine, it's what I do every night and it helps my back and hips SO much!
Hope those tips help!
Feel free to ask me any questions you have, I'm here for you!