Preterm labor occurs when regular contractions result in the opening of your cervix after week 20 and before week 37 of pregnancy.

Preterm labor can result in premature birth. The earlier premature birth happens, the greater the health risks for your baby. Many premature babies (preemies) need special care in the neonatal intensive care unit. Preemies can also have long-term mental and physical disabilities.

The specific cause of preterm labor often isn't clear. Certain risk factors might increase the chance of preterm labor, but preterm labor can also occur in pregnant women with no known risk factors.


Signs and symptoms of preterm labor include:

  • Regular or frequent sensations of abdominal tightening (contractions)
  • Constant low, dull backache
  • A sensation of pelvic or lower abdominal pressure
  • Mild abdominal cramps
  • Vaginal spotting or light bleeding
  • Preterm rupture of membranes — in a gush or a continuous trickle of fluid after the membrane around the baby breaks or tears
  • A change in type of vaginal discharge — watery, mucus-like or bloody

When to see a doctor

If you experience these signs or symptoms or you're concerned about what you're feeling, contact your health care provider right away. Don't worry about mistaking false labor for the real thing. Everyone will be pleased if it's a false alarm.

From Mayo Clinic to your inbox

Sign up for free and stay up to date on research advancements, health tips, current health topics, and expertise on managing health. Click here for an email preview.

To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and website usage information with other information we have about you. If you are a Mayo Clinic patient, this could include protected health information. If we combine this information with your protected health information, we will treat all of that information as protected health information and will only use or disclose that information as set forth in our notice of privacy practices. You may opt-out of email communications at any time by clicking on the unsubscribe link in the e-mail.

Risk factors

Preterm labor can affect any pregnancy. Many factors have been associated with an increased risk of preterm labor, however, including:

  • Previous preterm labor or premature birth, particularly in the most recent pregnancy or in more than one previous pregnancy
  • Pregnancy with twins, triplets or other multiples
  • Shortened cervix
  • Problems with the uterus or placenta
  • Smoking cigarettes or using illicit drugs
  • Certain infections, particularly of the amniotic fluid and lower genital tract
  • Some chronic conditions, such as high blood pressure, diabetes, autoimmune disease and depression
  • Stressful life events, such as the death of a loved one
  • Too much amniotic fluid (polyhydramnios)
  • Vaginal bleeding during pregnancy
  • Presence of a fetal birth defect
  • An interval of less than 12 months — or of more than 59 months — between pregnancies
  • Age of mother, both young and older
  • Black, non-Hispanic race and ethnicity


Complications of preterm labor include delivering a preterm baby. This can pose a number of health concerns for your baby, such as low birth weight, breathing difficulties, underdeveloped organs and vision problems. Children who are born prematurely also have a higher risk of cerebral palsy, learning disabilities and behavioral problems.


You might not be able to prevent preterm labor — but there's much you can do to promote a healthy, full-term pregnancy. For example:

  • Seek regular prenatal care. Prenatal visits can help your health care provider monitor your health and your baby's health. Mention any signs or symptoms that concern you. If you have a history of preterm labor or develop signs or symptoms of preterm labor, you might need to see your health care provider more often during pregnancy.
  • Eat a healthy diet. Healthy pregnancy outcomes are generally associated with good nutrition. In addition, some research suggests that a diet high in polyunsaturated fatty acids (PUFAs) is associated with a lower risk of premature birth. PUFAs are found in nuts, seeds, fish and seed oils.
  • Avoid risky substances. If you smoke, quit. Ask your health care provider about a smoking cessation program. Illicit drugs are off-limits, too.
  • Consider pregnancy spacing. Some research suggests a link between pregnancies spaced less than six months apart, or more than 59 months apart, and an increased risk of premature birth. Consider talking to your health care provider about pregnancy spacing.
  • Be cautious when using assisted reproductive technology (ART). If you're planning to use ART to get pregnant, consider how many embryos will be transferred. Multiple pregnancies carry a higher risk of preterm labor.
  • Manage chronic conditions. Certain conditions, such as diabetes, high blood pressure and obesity, increase the risk of preterm labor. Work with your health care provider to keep any chronic conditions under control.

If your health care provider determines that you're at increased risk of preterm labor, he or she might recommend taking additional steps to reduce your risk.

Feb. 08, 2022
  1. Lockwood CJ. Preterm labor: Clinical findings, diagnostic evaluation, and initial treatment. https://www.uptodate.com/contents/search. Accessed Oct. 15, 2019.
  2. Cunningham FG, et al., eds. Preterm birth. In: Williams Obstetrics. 25th ed. McGraw-Hill Education; 2018. https://accessmedicine.mhmedical.com. Accessed Oct.16, 2019.
  3. Frequently asked questions: Labor, delivery, and postpartum care FAQ087: Preterm (premature) labor and birth. American College of Obstetricians and Gynecologists. https://www.acog.org/Patients/FAQs/Preterm-Premature-Labor-and-Birth. Accessed Oct.14, 2019.
  4. American College of Obstetricians and Gynecologists. Practice Bulletin No. 171: Management of preterm labor. Obstetrics & Gynecology. 2016; doi:10.1097/AOG.0000000000001711. Reaffirmed 2019.
  5. Simhan HN, et al. Inhibition of acute preterm birth. https://www.uptodate.com/contents/search. Accessed Oct. 15, 2019.
  6. Robinson JN, et al. Preterm birth: Risk factors, interventions for risk reduction, and maternal prognosis. https://www.uptodate.com/contents/search. Accessed Oct. 15, 2019.
  7. DeCherney AH, et al., eds. Late pregnancy complications. In: Current Diagnosis & Treatment: Obstetrics & Gynecology. 12th ed. McGraw-Hill Education; 2019. https://accessmedicine.mhmedical.com. Accessed Oct. 16, 2019.
  8. American College of Obstetricians and Gynecologists. Practice Bulletin No. 142: Cerclage for the management of cervical insufficiency. Obstetrics & Gynecology. 2014; doi: 10.1097/01.AOG.0000443276.68274.cc.
  9. Resnik R, et al., eds. Preterm labor and birth. In: Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice. 8th ed. Elsevier; 2019. https://www.clinicalkey.com. Accessed Oct.16, 2019.
  10. Frequently asked questions: Labor, delivery, and postpartum care FAQ004: How to tell when labor begins. American College of Obstetricians and Gynecologists. https://www.acog.org/Patients/FAQs/How-to-Tell-When-Labor-Begins. Accessed Oct. 14, 2019.
  11. American College of Obstetricians and Gynecologists. Practice Bulletin No. 713: Antenatal corticosteroid therapy for fetal maturation. Obstetrics & Gynecology. 2017; doi: 10.1097/AOG.0000000000002237.
  12. Wick MJ (expert opinion). Mayo Clinic. Oct. 25, 2019.
  13. Norwitz ER. Progesterone supplementation to reduce the risk of spontaneous preterm birth. https://www.uptodate.com/contents/search. Accessed Oct. 15, 2019.
  14. Conde-Agudelo A, et al. Vaginal progesterone is as effective as cervical cerclage to prevent preterm birth in women with a singleton gestation, previous spontaneous preterm birth, and a short cervix: Updated indirect comparison meta-analysis. American Journal of Obstetrics & Gynecology. 2018; doi: 10.1016/j.ajog.2018.03.028.


Associated Procedures