Lower back pain is common during pregnancy due to hormonal changes and increased pressure on the spine. Sitting for long periods can exacerbate this pain. To alleviate it, try using a supportive chair or cushion, practicing good posture, taking breaks to stretch and walk around, and doing gentle exercises recommended by your healthcare provider. As for the burning sensation during urination, it could indicate a urinary tract infection (UTI), which is more common during pregnancy. UTIs should be promptly treated with antibiotics prescribed by your doctor to avoid complications. It's important to consult your healthcare provider about these symptoms for proper diagnosis and guidance throughout your pregnancy journey.