There are a lot of rules out there about practicing pregnant: don’t twist, don’t invert, don’t practice mula bandha, don’t backbend. “Why…where did these rules come from?” I never found any good yogic or scientific reasons to back up these claims that were satisfactory to me. I firmly believe that what is good for the mother, is good for the baby.
For me backbends have been a great way to to get lower back relief.
Somedays I use my swiss ball as a support when I don’t feel up to the full bridge (backbend).
You can modify your backbend to a half bridge, here is an example:
Be aware that all your ligaments will be a bit looser throughout your pregnancy due to “relaxin” (the body produces this during pregnancy because the bones and ligaments need to “soften” for childbirth…ligaments need to open around the hips so you can push the baby out, but your body doesn’t differentiate between ligaments in your hips and every other part of your body).
And remember backbends may not be for everyone during pregnancy…..
Your own intuitions will be sure to guide you in the right direction.