Any type of narcotic can cause your baby to have withdrawls once she is born, not to mention that some cause birth defects, preterm labor, etc.. Avoid medications as much as possible. I have severe migranes which increased in frequency since I became pregnant (I am 33 weeks with my first) and I just try to remember that I have 9 months to give my baby the best start in life that I can and I can deal with pain for that long. I would ask others and your doctor about alternative ways to ease your pain. I have had back problems also and my baby puts pressure on my nerve sometimes. I just started using a "maternity belt" and it gives a lot of support and keeps the baby from putting so much pressure on my lower pelvic area and nerves. Also a heating pad on my back sometimes helps, and sleeping with a pillow between my legs while laying on my side helps my body stay more in a straight line which helps back pain also. Try to take short walks a couple of times a day to stay strong and keep your blood circulating, but also get as much rest and feet up time as you can. drink lots and lots of water..........even though it will increase your potty breaks! I hope these things help. I had to figure most of them out on my own so am happy to share!
You should ask your doctor if its ok for you to take it because there is no studies to see how it effects the baby