Starting in my second trimester, I have been experiencing a lot of pain in my tail bone. Is this common? Is it something I should worry about when delivering?
The tailbone, called the coccyx, is connected to the rest of the vertebral column by the ligamental tissue that attaches between vertebrae. It normally sits in one position, with a little play, until it is snapped. Most people experience this hinge-like displacement in childhood. (My own met its fate after coming down a slide on my rear end.) You'll know you've snapped yours ("breaking the tail bone") when you land unceremoniously on your behind one day and see stars (I call this an astronomical injury). This pain due to the coccyx is called "coccygea" and takes about two months of creative sitting for the pain to slowly goes away.
But, the coccyx never really heals back the way it should. Because of this, anything mobilizing the coccyx can fire up tenderness. In pregnancy, the increase in size of the uterus will stretch and pull on the ligaments that go from the cervix to the tailbone. (These are called uterosacral ligaments.) Then, the hinge-like weakness of the coccyx comes into play and can cause intermittent tenderness.
This pain is harmless and definitely won't interfere with delivery. In fact, a lot of deliveries actually cause coccygea by displacing the coccyx posteriorly as the baby's head passes over it. This is a mechanical conciliatory gesture by the woman's body to allow successful passage through her pelvis.
After delivery, pending pediatrician approval, ibuprofen-like medicines can be very helpful for coccygea. (Ibuprofen is contraindicated during pregnancy.)