When you’re pregnant, the rules about what’s “normal” go right out the window. You wouldn’t normally think you could fit something the size of a watermelon in your belly or have your cervix dilate to the width of a cell phone. And yes, it’s even possible for your tailbone to shift shape. That’s because when you’re pregnant, your body secretes the hormone relaxin, which helps soften joints (and also makes it easier for that cantaloupe-size head to pass through the birth canal). Your tailbone (or in scientific terminology, coccyx) is made up of a half dozen little bones connected by small joints. As it does with other joints in your body, relaxin loosens up the ligaments in your tailbone to make them softer and more pliable. And yup, that can cause it to change shape (and sometimes make even sitting down painful). Some women do even break their tailbone during labor (ouch), but it usually heals on its own.
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