Some women experience very distinct signs of labor, while others do not. No one knows what causes labor to start or when it will start, but several hormonal and physical changes may indicate the beginning of labor:
Passing of the mucus plug
Effacement and dilation of the cervix
Lightening During Labor
The process of your baby settling or lowering into your pelvis just before labor is called lightening. Lightening can occur a few weeks or a few hours before labor. Because the uterus rests on the bladder more after lightening, you may feel the need to urinate more frequently.
Passing of the Mucus Plug
The mucus plug accumulates at the cervix during pregnancy. When the cervix begins to open wider, the mucus is discharged into the vagina and may be clear, pink, or slightly bloody. Labor may begin soon after the mucus plug is discharged or one to two weeks later.
During contractions, the abdomen becomes hard. Between contractions, the uterus relaxes and the abdomen becomes soft. The way a contraction feels is different for each woman, and may feel different from one pregnancy to the next. But labor contractions usually cause discomfort or a dull ache in your back and lower abdomen, along with pressure in the pelvis. Contractions move in a wave-like motion from the top of the uterus to the bottom. Some women describe contractions as strong menstrual cramps. Unlike false labor contractions or Braxton Hicks contractions, true labor contractions do not stop when you change your position or relax. Although the contractions may be uncomfortable, you will be able to relax in between contractions.
What's the Difference Between True Labor and False Labor?
Before "true" labor begins, you may have "false" labor pains, also known as Braxton Hicks contractions. These irregular uterine contractions are perfectly normal and may start to occur in your second trimester, although more commonly in your third trimester of pregnancy. They are your body's way of getting ready for the "real thing."