Yes it is normal unfortunately. The relaxin (hormone) in your body has loosened your pelvic ligaments, causing pain when you are weight bearing (i.e. standing, walking). Usually worse with single legged activity (stair climbing). You can try to see if a pelvic girdle helps the pain. But otherwise, the usual recommendation is to rest up to delivery. After delivery, the pain may persist for a period of time. This is also normal. Gradually increase your walking distance. Get help as needed so you don't stress yourself physically or mentally.