Overview

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 risk, but preterm labor can also occur in pregnant women with no known risk factors. Understand the signs and symptoms of preterm labor and next steps.

Symptoms

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.

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
  • Problems with the uterus, cervix 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 and diabetes
  • 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 six months between pregnancies
  • Infection of tissues that surround and support your teeth (periodontal disease)

Complications

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 learning disabilities and behavioral problems.

Prevention

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. Some research suggests that a diet high in polyunsaturated fats (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 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 implanted. Multiple pregnancies carry a higher risk of preterm labor.

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, such as:

  • Taking preventive medications. If you have a history of premature birth, your health care provider might suggest weekly shots of a form of the hormone progesterone called hydroxyprogesterone caproate starting during your second trimester and continuing until week 37 of pregnancy. In addition, your health care provider might offer progesterone, which is inserted in the vagina, as a preventive measure against preterm birth. If you are diagnosed with a short cervix before week 24 of pregnancy, your health care provider might also recommend use of progesterone until week 37 of pregnancy.
  • Managing chronic conditions. Certain conditions, such as diabetes and high blood pressure, increase the risk of preterm labor. Work with your health care provider to keep any chronic conditions under control.

If you have a history of preterm labor or premature birth, you're at risk of a subsequent preterm labor. Work with your health care provider to manage any risk factors and respond to early warning signs and symptoms.

Feb. 20, 2018
References
  1. Lockwood CJ. Diagnosis of preterm labor. https://www.uptodate.com/contents/search. Accessed Dec. 11, 2017.
  2. Cunningham FG, et al. Preterm labor. In: Williams Obstetrics. 24th ed. New York, N.Y.: The McGraw-Hill Companies; 2014. http://accessmedicine.mhmedical.com. Accessed Dec. 11, 2017.
  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 Nov. 29, 2017.
  4. American College of Obstetricians and Gynecologists (ACOG) Committee on Practice Bulletins — Obstetrics. ACOG Practice Bulletin No. 171: Management of preterm labor. Obstetrics & Gynecology. 2016;128:e155.
  5. Simhan HN, et al. Inhibition of acute preterm birth. https://www.uptodate.com/contents/search. Accessed Dec. 11, 2017.
  6. Robinson JN, et al. Preterm birth: Risk factors and interventions for risk reduction. https://www.uptodate.com/contents/search. Accessed Dec. 11, 2017.
  7. DeCherney AH, et al. Late pregnancy complications. In: Current Diagnosis & Treatment Obstetrics & Gynecology.11th ed. New York, N.Y.: The McGraw-Hill Companies; 2013. http://accessmedicine.mhmedical.com. Accessed Dec. 19, 2017.
  8. American College of Obstetricians and Gynecologists (ACOG) Committee on Practice Bulletins — Obstetrics. ACOG Practice Bulletin No. 142: Cerclage for the management of cervical insufficiency. Obstetrics & Gynecology. 2014;123:372. Reaffirmed 2016.
  9. Creasy RK, et al., eds. Preterm labor and birth. In: Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice. 7th ed. Philadelphia, Pa.: Saunders Elsevier; 2014. https://www.clinicalkey.com. Accessed Dec. 19, 2017.
  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 Nov. 29, 2017.
  11. American College of Obstetricians and Gynecologists (ACOG) Committee on Obstetric Practice. ACOG Practice Bulletin No. 677: Antenatal corticosteroid therapy for fetal maturation. Obstetrics & Gynecology. 2016;128:187.
  12. Caritis S, et al. Management of pregnant women after inhibition of acute preterm labor. https://www.uptodate.com/contents/search. Accessed Dec. 20, 2017.
  13. Norwitz ER. Progesterone supplementation to reduce the risk of spontaneous preterm birth. https://www.uptodate.com/contents/search. Accessed Dec. 20, 2017.