Backbending while pregnant can bring a range of sensations from most delicious to most painful. These poses will open you up only where you need it most and reduce risk of injury.
If pregnant women practice backbends as they did pre-pregnancy, they’re likely in for more pain than gain. We can see how by looking at the shape of the spine of a pregnant woman: Typically she will have exaggerated lordosis of the lumbar spine (overarching of the lower back) and increased kyphosis of the thoracic spine (rounding forward of the upper back). Both are due to the weight of the growing and stretching belly. Muscularly, in an effort to support the baby, her chest muscles tighten (causing the upper back and shoulders to round forward) while the abdominals get overstretched. Later in pregnancy, the abs are just barely holding on and the low back muscles contract to compensate.
When we consider this shape, we can easily see that the only part of the spine that needs to backbend is the upper back. Deepening the arch in the lumbar spine further stretches the already overstretched abdominals, putting mamas at risk for developing diastasis recti (the tearing away of the rectus abdominis from the fibrous tissue that connects them, called the linea alba) and pubic symphysis dysfunction (inflammation and pain of the pubic bone). Deep backbends can also lead to sacroiliac joint imbalances, which can lead to sciatica (already a common complaint among pregnant women). With the hormone relaxin present in the body during pregnancy, all of the ligaments of the pelvis are loose. If a backbend isn't performed perfectly symmetrically, one side of the pelvis easily slips up at the SI joint causing low back pain and potentially sciatica. By practicing backbends that target only the thoracic spine, we get the delicious sensation of opening only where we really need it.