There are two different kinds of contractions. Braxton-Hicks contractions, also called false labor, prepare your body for labor and delivery. Labor contractions signal the beginning of childbirth.

What causes contractions?

Braxton-Hicks (false labor)
These contractions soften and thin the cervix (the opening to the uterus through which the baby passes during delivery). The contractions tend to increase in the weeks right before your due date. With Braxton-Hicks:

  • You may feel tightening of your uterus muscles at irregular intervals or a squeezing sensation in your lower abdomen and groin.
  • Sometimes you can just barely sense these contractions, feeling only a painless tightening. At other times, the contractions can be strong or painful.
  • These contractions tend to come and go unpredictably and tend to show up in the afternoon or evening. They are more common when women are tired or have had a lot of physical activity during the day.

Labor contractions

Most pregnancies generally last between 37-42 weeks. (Your due date is calculated as 40 weeks after the first day of your last menstrual period.) Labor contractions signal the beginning of childbirth. These contractions come at regular intervals, usually move from the back to the lower abdomen, last between 30-70 seconds, and get stronger and closer together over time. For some women, there is no advance sign that labor is near. Others experience cramps, contractions and discomfort for weeks before delivery.

Nobody knows exactly what causes labor to begin, but the following signs may help signal that labor is near:

  • The feeling that the baby has settled lower in your belly. This can occur a few weeks or a few hours before labor.
  • Increased vaginal discharge that is clear, pink or slightly bloody. This can occur a few days or immediately before labor.
  • Your water "breaks" (fluid leaks or gushes from your vagina). This occurs at the start of or during labor.

Preterm labor

Painful, regular contractions before 37 weeks of pregnancy may be a sign of preterm labor. Preterm labor occurs in about 1 of 10 births in the United States. Compared to babies born after 37 weeks, preterm babies are at greater risk of:

  • Hospitalization
  • Long-term health problems
  • Death in infancy

Preterm labor can happen to any woman. There is no single cause of preterm labor. Learn more about preterm labor.

What should you do if you have contractions?

Towards the end of your pregnancy, you may have regular contractions that don't immediately lead to changes in your cervix or progress to labor. If you go to the hospital only to find out that you are having false labor, don't feel bad about it. It’s sometimes hard to know the difference between real and false labor. To tell if labor has begun, your health care provider must examine your cervix.

When you first feel contractions, time them. Write down how much time passes from the start of one contraction to the next. Make a note of how strong the contractions feel. Keep a record of your contractions for an hour. Walk or move around to see whether the contractions stop when you change positions.

You are probably experiencing false labor if:

  • The contractions stop when you walk or stop on their own.
  • The contractions are irregular.
  • The contractions don't get stronger or closer together over time.

When should you call your health care provider about contractions?

Contact your health care provider right away if:

  • You are having contractions that trouble you, especially if they become very painful or if you think you are having preterm labor (labor before the 37th week of pregnancy).
  • Your contractions are between 5 and 10 minutes apart.
  • Your water breaks, especially if the fluid is stained dark, greenish brown.
  • You experience vaginal bleeding.
  • You can no longer walk or talk during contractions.
  • You are concerned about your health or the health and well-being of the baby.

Last reviewed: December, 2013