Anyhow, the books' recommended affirmations for sciatica:
"I move into my greater good. My good is everywhere, and I am secure and safe."
"Coping with Sciatica" had more suggestions for poses that can alleviate sciatica, and I also discovered another YJ practice for sciatica. However I'm not sure if all the postures are appropriate for pregnant women, such as the twists.
If you have other suggestions for dealing with sciatica, please let me know. My ass will thank you! ;)