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What is preterm labor?

What is preterm birth?

What are the signs and symptoms of preterm labor?

Can preterm labor stop on its own?

What are the risk factors for preterm labor?

What are the risk factors for preterm birth?

What will happen if I have signs of preterm labor?

What tests will my ob-gyn or other obstetric care provider order?

If a woman has preterm labor, does that mean she will have a preterm birth?

How is preterm labor managed?

What happens if my labor is too far along to be stopped?

What medications are given to prepare a fetus for preterm birth?

What do corticosteroids do?

When are corticosteroids given?

What does magnesium sulfate do?

When is magnesium sulfate given?

What do tocolytics do?

When are tocolytics given?

What will happen after birth if I have a preterm baby?

What should I know about preterm birth and future pregnancies?

Are there treatments that can help to prevent preterm birth?

Will I be put on bed rest if I am at risk of preterm birth?

Glossary

What is preterm labor?

A typical pregnancy lasts about 40 weeks. Preterm labor is labor that starts before 37 weeks of pregnancy. Going into preterm labor does not automatically mean that a woman will have a preterm birth. But preterm labor needs medical attention right away.

 

What is preterm birth?

Preterm birth is the birth of a baby before 37 weeks. Preterm babies may be born with serious health problems. Some health problems, like cerebral palsy, can be lifelong. Other problems, such as learning disabilities, may appear later in childhood or even in adulthood.

 

What are the signs and symptoms of preterm labor?

Preterm labor contractions lead to changes in the cervix. The changes include effacement (thinning of the cervix) and dilation (opening of the cervix). Signs and symptoms include the following:

  • Mild abdominal cramps, with or without diarrhea
  • A change in type of vaginal discharge—watery, bloody, or with mucus
  • An increase in the amount of discharge
  • Pelvic or lower abdominal pressure
  • Constant, low, dull backache
  • Regular or frequent contractions or uterine tightening, often painless
  • Ruptured membranes (your water breaks with a gush or a trickle of fluid)

If you have any signs or symptoms of preterm labor, do not wait. Call the office of your obstetrician–gynecologist (ob-gyn) or other obstetric care provider right away or go to the hospital. Preterm labor is diagnosed when changes in the cervix are found after contractions start.

 

Can preterm labor stop on its own?

In some cases, yes. For about 3 in 10 women, preterm labor stops on its own. If it does not stop, treatments may be given to try to delay birth. In some cases, these treatments may reduce the risk of complications if the baby is born.

 

What are the risk factors for preterm labor?

Preterm labor can happen to anyone without warning. But there are some factors that can increase the risk of preterm labor, including:

  • Preterm birth in a past pregnancy
  • Having a short cervix early in pregnancy
  • Past gynecologic conditions or surgeries
  • Current pregnancy complications
  • Lifestyle factors (see “What are the risk factors for preterm birth”)

 

What are the risk factors for preterm birth?

Many women who have preterm births have no known risk factors. Some risk factors include the following:

Medical History

  • Past preterm birth
  • Short cervix (measured during a transvaginal ultrasound exam)
  • Early cervical dilation (measured during a pelvic exam)
  • Past procedures on the cervix
  • Injury during a past delivery

Pregnancy Complications

  • Carrying more than one fetus
  • Vaginal bleeding during pregnancy
  • Infections during pregnancy

Lifestyle Factors

  • Low prepregnancy weight
  • Smoking during pregnancy
  • Dietary deficiencies

Other Factors

  • Younger than 17 or older than 35
  • African American race

 

What will happen if I have signs of preterm labor?

Your ob-gyn or other obstetric care provider may do a pelvic exam to see if your cervix has started to change. You may need to be examined several times over a period of a few hours. Your contractions also may be monitored.

 

What tests will my ob-gyn or other obstetric care provider order?

There are several tests that may be ordered:

  • An ultrasound exam to estimate gestational age or to check the size of your fetus.
  • A transvaginal ultrasound exam to measure the length of the cervix.
  • A vaginal swab to test for the presence of fetal fibronectin. This is a protein that acts like a glue, helping the amniotic sac stay connected to the inside of the uterus.

 

If a woman has preterm labor, does that mean she will have a preterm birth?

It is difficult for health care professionals to predict which women with preterm labor will go on to have preterm birth. The goals of monitoring and treatment are to reduce the risk of preterm birth and protect the health of you and your fetus.

 

How is preterm labor managed?

Your ob-gyn or other obstetric care provider will manage preterm labor based on what he or she thinks is best for your health and the fetus’s health. If the fetus would benefit from a delay in delivery, medications may be given to:

  • Help the organs mature more quickly
  • Reduce the risk of certain complications
  • Attempt to delay delivery for a short time

 

What happens if my labor is too far along to be stopped?

When preterm labor is too far along to be stopped, delivery may be necessary. If your hospital does not have the resources to care for preterm babies, your ob-gyn or other obstetric care provider may recommend transfer to another hospital with these resources.

 

What medications are given to prepare a fetus for preterm birth?

Medications that help prepare a fetus for preterm birth include corticosteroids, magnesium sulfate, and tocolytics.

 

What do corticosteroids do?

Corticosteroids can help speed up development of the fetus’s lungs, brain, and digestive organs. A single course of corticosteroids may be recommended between 24 and 34 weeks of pregnancy for women who are at risk of delivery within 7 days, including for women with ruptured membranes and those carrying more than one fetus.

 

When are corticosteroids given?

  • If a woman is likely to give birth within 1 week, a single course of corticosteroids is given. It takes 2 days after the first dose is given for the most benefits to occur, but there is some benefit in the first 24 hours.
  • A repeat course of corticosteroids can be given if a previous course was given more than 14 days ago and there is risk for delivery within 7 days.

 

What does magnesium sulfate do?

When given before preterm birth, magnesium sulfate may reduce the risk of cerebral palsy and problems with physical movement.

 

When is magnesium sulfate given?

This medication may be given if a woman is less than 32 weeks pregnant and at risk of delivery within the next 24 hours. Magnesium sulfate may cause minor side effects, including flushing, hot flashes, blurred vision, and weakness.

 

What do tocolytics do?

Tocolytics are medications used to delay delivery, sometimes for up to 48 hours. If delivery is delayed even a few hours, it may allow more time to give corticosteroids or magnesium sulfate. This delay also may allow time for transfer to a hospital with specialized care for preterm babies.

 

When are tocolytics given?

Tocolytics are given when an ob-gyn or other obstetric care provider thinks the benefits of the treatment outweigh the risks. Tocolytics typically are not given when:

  • There are preterm labor symptoms but no changes in the cervix
  • It is thought that delivery would be better for the woman or her baby
  • Preterm labor has stopped

Tocolytics can have side effects for the woman, some of which can be serious. The side effects differ depending on the drug.

 

What will happen after birth if I have a preterm baby?

If labor does not stop and a woman gives birth early, a team of health care professionals will take care of the baby. The team may include a neonatologist.

The care a baby needs depends on how early he or she is born. A neonatal intensive care unit (NICU) provides specialized care for preterm babies. Some babies need to stay in the NICU for weeks or even months.

 

What should I know about preterm birth and future pregnancies?

A significant risk factor for preterm birth is a past preterm birth. Women with past preterm birth are 2 to 3 times more likely to deliver preterm in the future. This risk increases with each preterm birth. But some women will deliver preterm without any clear risk factors.

 

Are there treatments that can help to prevent preterm birth?

Yes. If you are at risk of preterm birth, talk with your ob-gyn or other obstetric care provider about treatments that may help prevent it. Treatments may include:

  • Progesterone shots—If you have had a preterm birth with a single baby, and you are pregnant with a singleton again, you may be offered progesterone shots starting at 16 to 24 weeks of pregnancy. This hormone may help prevent another preterm birth. These shots are usually continued weekly until 36 weeks, unless delivery happens sooner.
  • Vaginal progesterone—This treatment may be given if you have not had a preterm birth before, but you have a very short cervix at 24 weeks of pregnancy or earlier. Vaginal progesterone is a gel or suppository that you place in your vagina every day until 37 weeks, unless delivery happens sooner.
  • Cerclage—If you have a short cervix and have had a preterm birth before, a procedure called cerclage also may be done. In cerclage, the cervix is closed with one or more stitches.

 

Will I be put on bed rest if I am at risk of preterm birth?

No, bed rest is not recommended for women at risk of preterm birth. Bed rest can increase the risk of blood clots, bone weakening, and loss of muscle strength.

Glossary

Cerclage: A procedure in which the cervical opening is closed with stitches to prevent or delay preterm birth.

Cerebral Palsy: A disorder of the nervous system that affects movement, posture, and coordination. This disorder is present at birth.

Cervix: The lower, narrow end of the uterus at the top of the vagina.

Complications: Diseases or conditions that happen as a result of another disease or condition. An example is pneumonia that occurs as a result of the flu. A complication also can occur as a result of a condition, such as pregnancy. An example of a pregnancy complication is preterm labor.

Corticosteroids: Drugs given for arthritis or other medical conditions. These drugs also are given to help fetal lungs mature before birth.

Dilation: Widening the opening of the cervix.

Effacement: Thinning out of the cervix.

Fetal Fibronectin: A protein that is produced by fetal cells. It helps the amniotic sac stay connected to the lining of the uterus.

Fetus: The stage of human development beyond 8 completed weeks after fertilization.

Gestational Age: How far along a woman is in her pregnancy, usually reported in weeks and days.

Hormone: A substance made in the body that controls the function of cells or organs.

Magnesium Sulfate: A drug that may help prevent cerebral palsy when it is given to women in preterm labor who may deliver before 32 weeks of pregnancy.

Neonatal Intensive Care Unit (NICU): A special part of a hospital in which sick newborns receive medical care.

Neonatologist: A doctor who specializes in the diagnosis and treatment of disorders that affect newborn infants.

Obstetric Care Provider: A health care professional who cares for a woman during pregnancy, labor, and delivery. These professionals include obstetrician–gynecologists (ob-gyns), certified nurse–midwives (CNMs), maternal–fetal medicine specialists (MFMs), and family practice doctors with experience in maternal care.

Obstetrician–Gynecologist (Ob-Gyn): A doctor with special training and education in women’s health.

Pelvic Exam: A physical examination of a woman’s pelvic organs.

Prepregnancy: Before pregnancy.

Preterm: Less than 37 weeks of pregnancy.

Progesterone: A female hormone that is made in the ovaries and prepares the lining of the uterus for pregnancy.

Tocolytics: Drugs used to slow contractions of the uterus.

Transvaginal Ultrasound Exam: A type of ultrasound in which the device is placed in your vagina.

Ultrasound Exam: A test in which sound waves are used to examine inner parts of the body. During pregnancy, ultrasound can be used to check the fetus.

Uterus: A muscular organ in the female pelvis. During pregnancy, this organ holds and nourishes the fetus.


If you have further questions, contact your obstetrician–gynecologist.

FAQ087. Copyright June 2020 by the American College of Obstetricians and Gynecologists


This information is designed as an educational aid to patients and sets forth current information and opinions related to women’s health. It is not intended as a statement of the standard of care, nor does it comprise all proper treatments or methods of care. It is not a substitute for a treating clinician’s independent professional judgment. Read ACOG’s complete disclaimer.