Contractions

Causes of Contractions During Pregnancy
Braxton-Hicks contractions. These contractions prepare your body for the hard work of labor and delivery. They soften and thin the cervix (the “exit route” from the uterus through which the baby passes during delivery). These contractions tend to increase in the weeks right before your due date. During these contractions, you may feel tightening of your uterus muscles at irregular intervals or a “squeezing” 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—particularly when you are tired or have had a lot of physical activity during the day. 

The following table shows the key differences between “false” and true labor contractions

Braxton-Hicks contractions	Labor contractions
Are irregular	Are regular, lasting about 30-70 seconds each
Do not get closer together over time	Get closer together over time
Don't get stronger over time	Get progressively stronger over time
Sometimes are felt only in the lower abdomen and groin	Often start at your back and move to your front
May stop when you change positions or walk around	Do not stop when you change positions or walk around

 

Labor. 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 the 37th week of pregnancy may be a sign of preterm labor, which occurs in about 1 of 8 births in the United States. Babies who are born preterm are at higher risk of needing hospitalization, of having long-term health problems, and of dying than babies born after the 37th week.

Preterm labor can happen to any woman. There is no single cause of preterm labor. Some women are at higher risk of preterm labor than others:

• Women who have had a previous premature birth
• Women who are pregnant with carrying twins, triples or more
• Women with certain uterine or cervical abnormalities

Other factors, such as smoking, stress, and infection, may also increase a woman's risk. For more information on risk factors, read the article Are You at Risk?

Preterm labor may sometimes be stopped with a combination of medication and rest. More often, birth can be delayed just long enough to transport the woman to a hospital with a neonatal intensive care unit (NICU). In the hospital, the woman is given a drug to help speed up her baby's lung development and an antibiotic to protect the newborn from infection.

Contractions: What You Can Do
If you experience painful, regular contractions before the 37th week of pregnancy, call your health care provider or go to the hospital right away.

After 37 weeks of pregnancy, you may have regular contractions that don't immediately lead to changes in your cervix or progress to labor. These contractions are called “false labor.” If you go to the hospital only to find out that you are having false labor, don't feel bad about it. Many women have trouble telling the two apart. To tell if labor has begun, your health care provider must examine your cervix.

When you first feel contractions, time them to see 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. Be sure to 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 to Talk to Your Health Care Provider
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).

Preterm labor. The signs of preterm labor include:

• Contractions (your abdomen tightens like a fist) every 10 minutes or more often
• Change in vaginal discharge (leaking fluid or bleeding from your vagina)
• Pelvic pressure—the feeling that your baby is pushing down
• Low, dull backache
• Cramps that feel like your period
• Abdominal cramps with or without diarrhea

You don't need to have all the symptoms to have preterm labor. Take action even if you have only one. If you are experiencing preterm labor, your health care provider may tell you to:

• Come into the office or go to the hospital to be checked.
• Stop what you're doing. Rest on your left side for one hour.
• Drink 2-3 glasses of water or juice (not coffee or soda).

If the symptoms get worse or do not go away after one hour, call your health care provider again or go to the hospital. If the symptoms go away, relax for the rest of the day. If the symptoms stop but come back, call your health care provider again or go to the hospital.

Labor. Call your health care provider when:

• 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.