I have an old back injury which has flared up with my pregnancy. I've been experiencing problems on and off since about 16 weeks. Mine nearly always flares up on the weekends so I've worked out that the extra time on my feet and doing house work is the culprit.

To help with my back pain I've done the following:
- got my DH to do A LOT more around the house. He's always helped out but now he has to do the vacumming, mopping, clean the shower, etc. I'm careful to watch how I bend when I'm doing housework and hanging out washing now too.
- I have been to the physio several times which helped relieve the severe pain and they have given me some exercises to help strenghten my glutes - the area tha suffers the most when my back packs it in
- I use a heat pack while watching TV and take one to bed as well
- a good soak in a warm bath really helps to relieve the tension
- I have a belly belt now too - my physio got it for me - and I wear it on weekends for extra support when I'm doing housework

Back pain in pregnancy is terrible. Try to take it easy and be very mindful of your posture and how you bend to pick things up. Simple things like doing the dusting plays havoc on my back.

HTH!