Perineal tears during childbirth occur when the baby's head passes through the expanded vaginal wall, in cases where the baby's head is too large for the vaginal wall to stretch or the baby's head is normal but the vaginal wall is not elastic enough. Tears usually occur in the skin and subcutaneous area of the vagina and vulva, and usually heal on their own after a few weeks. In some cases, the tear is deeper and requires treatment.