Well yes, pregnancy hormones do make your joints, muscles and lower body relax to accommodate the growing baby and prepare for its delivery. This can cause a persistent low back ache, which can worsen if you sit , stand or lie down in a particular position for too long. A backward tilted or retroverted uterus can put pressure on your spine and hips and cause a lot of pain. It can also be due to threatened abortion, pelvic inflammatory disease, constipation and gas. Do discuss this with your doctor and get yourself examined. Take care!