I have just been looking on the net, because I'm worried about the loud cracking from my 15 week old baby's back bones. When she cries, she tends to hurl herself backwards and it's hard to hold her. I just picked her up, and I mustn't have been holding her high enough. It felt like it cracked all along her spine. I myself have always had cracking joints, in particular, my hips, but so far I think her hips are fine, and they've been checked. It's just quite distressing, My partner and I have heard her back crack before and she hasn't really complained, but this time she cried as if in pain. So when she eventually calmed down, I lightly ran my fingers along her back to see if it was tender. She didn't seem hurt and didn't cry out. From my own experience with cracking joints, you are told it's pockets of trapped air, or growing pains, but there isn't much you can do. Looking on NHS Direct, has brought up the possibility of rickets. I feel I have a good balanced diet, but as I'm fully breastfeeding, I'm wondering, should I or my baby be taking Vitamin D supplements,and how long is sufficient sunlight exposure per day?