If this is your first baby, lightening may occur weeks in advance of labor. In women who have had children, it usually doesn't happen until labor begins. When lightening does occur, you'll notice a change in the shape of your abdomen as it shifts down and forward. In addition to being able to breathe more deeply when the baby drops down into your pelvis, you'll probably feel the need to urinate more often, much as you did in the first trimester, because of the increased pressure on your bladder.
Some women also feel pressure or aches and pains in their pelvic joints and perineum.
It is also not unusual to feel sharp twinges in the perineal area as the baby's head presses on the pelvic floor. Your doctor will examine you during the last weeks of pregnancy to find whether engagement has occurred. Lately I've been having burning and numbness in my hands. These sensations are starting to wake me up during the night. You may be having symptoms of carpal tunnel syndrome.