Low back pain is quite common and can stem from the spine, muscles or nerves. Sciatic, a pinching of the sciatic nerve is a common work-related problem, and can also occur during pregnancy.
Because the lower back supports the majority of your body weight it has to work harder. This is why building a strong core is important as this muscle group helps to support the back during lifting, exercise and other daily activities.
If you are experiencing lower back pain consider getting an ergonomically designed chair that supports your back. And make sure to change posistion often even if you cant leave the desk or need to stay in the same spot for a long time.
Make sure to exercise and stretch on a regular basis. Or look her for help: