Hi dear, Thanks for choosing Healthcare magic. It s normal to have back pain during pregnancy, specially second trimester. and there are many reasons for this could happen among those are weight gain the weight gain could cause some pinched nerve in your back leading to the back pain, another cause could be due to a hormone known as relaxin. While this hormone relaxes joints it can cause loosening or swelling in your ligaments which again might lead to pain. However there could be some underlying disorders that could be the cause of your back pain such as kidney stones or water in kidney (hydronephrosis), these are common in pregnancy and needs to be checked by running some tests such as urine analysis, and kidney ultrasound. My suggestion is that you visit a Doctor to rule out kidney stones or hydronephrosis, once these are ruled out then you can follow a physiotherapy to relief your back pain, also make sure to avoid any heavy work or lifting, sit with your back straight. many people reported that putting ice compress on back helps relieve pain. When sleeping make sure you sleep on the side with your knees bent and pillow between knees to help ease pain at night. Overall i doubt you have anything to worry about so don t stress yourself. I would advice to take a pregnancy leave from work if possible as that would help you relax more. I hope this helped If you have more questions don t hesitate to ask. Wish you and your upcoming baby all the best.