I am only in my first trimester as a first time momma to be, but I also happen to be a labor and delivery nurse with over 2 years of experience. As your baby becomes more engaged into your pelvis, your hips have to open up more to accommodate that sweet fuzz covered head! Your body is even releasing a hormone called relaxin to help the joint of the pelvis open up. My best advice is warm showers, lots of water (at LEAST 8 ounces every hour you are awake) and sitting/bouncing on a birthing ball!