You have practice contractions. Around week 30, you may have begun to feel Braxton Hicks blips. Even if you know they're not real, tell your doc what you're experiencing.
Your cervix starts to dilate. About two to four weeks before delivery, your body "lightens" as the baby drops lower into your pelvis and pushes against your cervix, causing it to thin (efface) and open (dilate). This can continue for the remaining weeks until labor.
There's discharge. As your cervix thins and opens, the mucus plug that's been protecting it falls out. You may notice blood-tinged vaginal discharge called bloody show.
Your water breaks. If you're among the 10 percent of women whose amniotic sac ruptures, you'll feel a trickle or gush of colorless, odorless fluid. (Dark, greenish, bloody, or foul-smelling discharge requires immediate attention.) Most babies are delivered within 24 hours to prevent infection.