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Your baby "drops."
If this is your first pregnancy, you may feel what's known as "lightening" a few weeks before labor starts. You might detect a heaviness in your pelvis as this happens and notice less pressure just below your ribcage, making it easier to catch your breath.
You note more Braxton Hicks contractions.
More frequent and intense Braxton Hicks contractions can signal pre-labor, during which your cervix ripens (see below) and the stage is set for true labor. Some women experience a crampy, menstrual-like feeling during this time.
Sometimes, as true labor draws near, Braxton Hicks contractions become relatively painful and strike as often as every ten to 20 minutes, making you wonder whether true labor has started. But if the contractions don't get longer, stronger, and closer together and cause your cervix to dilate progressively, then what you're feeling is probably so-called false labor.
Your cervix starts to ripen.
In the days and weeks before delivery, Braxton Hicks contractions may do the preliminary work of softening, thinning, and perhaps opening your cervix a bit. (If you've given birth before, your cervix is more likely to dilate a centimeter or two before labor starts, but keep in mind that even being 40 weeks pregnant with your first baby and 1 centimeter dilated is no guarantee that labor is imminent.)
When you're at or near your due date, your practitioner may do a vaginal exam during your prenatal visit to see whether your cervix has started to change.
You pass your mucus plug or notice "bloody show."
You may pass your mucus plug — the small amount of thickened mucus that has sealed your cervical canal during the last nine months — if your cervix begins to dilate as you get close to labor.
The plug may come out in a lump or as increased vaginal discharge over the course of several days. The mucus may be tinged with brown, pink, or red blood, which is why it's referred to as "bloody show." Having sex or a vaginal exam can also disturb your mucus plug and cause you to see some blood-tinged discharge, even when labor isn't going to start in the next few days.