Typically we treat pregnant women for low back pain and groin pain. Around the start of the third trimester, your body produces a hormone called Relaxin which loosens all ligaments, most notably in the pelvis to allow increase in birth canal size. This also often causes pelvic instability.
Treatment involves pelvic assessment and treatment, manual therapy to reduce protective muscle tightness, and usually some external support like taping or a pelvic brace. In most cases, this eases the problem.
After child birth, the back pain settles, but we often see women re-present with neck and shoulder pain from nursing at about 6 weeks postpartum.
Being pregnant or having a newborn is hard enough, don’t try to put up with unnecessary pain on top of everything else.