Overview

Preterm labor occurs when regular contractions result in the opening of your cervix before 37 weeks of pregnancy. A full-term pregnancy should last about 40 weeks.

If your preterm contractions result in preterm labor, your baby will be born early. 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.

While the specific cause of preterm labor often isn't clear, certain risk factors may up the odds of early labor. But, preterm labor can also occur in pregnant women with no known risk factors. Still, it's a good idea to know if you're at risk of preterm labor and how you might help prevent it.

Symptoms

For some women, the signs and symptoms of preterm labor are unmistakable. For others, they're more subtle. During pregnancy, be on the lookout for:

  • Regular or frequent painful contractions — a tightening sensation in the abdomen
  • Constant low, dull backache
  • A sensation of pelvic or lower abdominal pressure
  • Mild abdominal cramps
  • Diarrhea
  • Vaginal spotting or bleeding
  • Watery vaginal discharge (water breaking) — in a gush or a trickle
  • A change in vaginal discharge

If you're concerned about what you're feeling — especially if you have vaginal bleeding accompanied by abdominal cramps or pain — 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 and many women who have preterm labor have no known risk factors. 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
  • Certain problems with the uterus, cervix or placenta
  • Smoking cigarettes or using illicit drugs
  • Certain infections, particularly of the genital tract
  • Some chronic conditions, such as high blood pressure and diabetes
  • Being underweight or overweight before pregnancy, or gaining too little or too much weight during pregnancy
  • Stressful life events, such as the death of a loved one
  • Red blood cell deficiency (anemia), particularly during early pregnancy
  • Too much amniotic fluid (polyhydramnios)
  • Pregnancy complications, such as preeclampsia
  • Vaginal bleeding during pregnancy
  • Presence of a fetal birth defect
  • Little or no prenatal care
  • An interval of less than six months since the last pregnancy

Also, having a short cervical length or the presence of fetal fibronectin — a substance that acts like a glue between the fetal sac and the lining of the uterus — in your vaginal discharge has been linked to an increased risk of preterm labor.

While some past research suggested that gum disease might be linked with premature birth, treatment of periodontal disease during pregnancy hasn't been proved to reduce the risk of premature birth.

Complications

Many women diagnosed with preterm labor deliver at or near term. However, there are no medications or surgical procedures to stop preterm labor, once it has started. In some cases, preterm labor associated with problems such as an infection or smoking can be managed by treating the infection or quitting smoking.

Preterm labor could lead to premature birth. This can pose a number of health concerns, 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, even if you think they're silly or unimportant. 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 for exams and tests.
  • Eat a healthy diet. During pregnancy, you'll need more folic acid, calcium, iron and other essential nutrients. A daily prenatal vitamin — ideally starting a few months before conception — can help fill any gaps.
  • Avoid risky substances. If you smoke, quit. Smoking might trigger preterm labor. Illicit drugs are off-limits, too.

    In addition, medications of any type — even those available over-the-counter — deserve caution. Get your health care provider's OK before taking any medications or supplements.

  • 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 (Makena) during your second trimester. In additional, your doctor might offer progesterone, which is inserted in the vagina, as a preventive measure against preterm birth.
  • Limiting certain physical activities. If you're at risk of preterm labor or develop signs or symptoms of preterm labor, your health care provider might suggest avoiding heavy lifting or spending too much time on your feet.
  • 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.

Preterm labor care at Mayo Clinic

Oct. 19, 2016
References
  1. Lockwood CJ. Overview of preterm labor and birth. http://www.uptodate.com/home. Accessed Sept. 30, 2014.
  2. Cunningham FG, et al. Williams Obstetrics. 24th ed. New York, N.Y.: The McGraw-Hill Companies; 2014. http://accessmedicine.mhmedical.com/book.aspx?bookid=1057. Accessed Oct. 3, 2014.
  3. Frequently asked questions. Labor, delivery and postpartum care FAQ087. Preterm (Premature) labor and birth. American College of Obstetricians and Gynecologists. http://www.acog.org/Patients/FAQs/Preterm-Premature-Labor-and-Birth. Accessed Sept. 30, 2014.
  4. American College of Obstetricians and Gynecologists (ACOG) Committee on Practice Bulletins — Obstetrics. ACOG Practice Bulletin No. 127: Management of preterm labor. Obstetrics & Gynecology. 2012;119:1308.
  5. Norwitz ER. Prevention of spontaneous preterm birth. http://www.uptodate.com/home. Accessed Sept. 30, 2014.
  6. Robinson JN, et al. Risk factors for preterm labor and delivery. http://www.uptodate.com/home. Accessed Sept. 30, 2014.
  7. DeCherney AH, et al. Current Diagnosis & Treatment Obstetrics & Gynecology.11th ed. New York, N.Y.: The McGraw-Hill Companies; 2013. http://accessmedicine.mhmedical.com/book.aspx?bookid=498. Accessed Oct. 3, 2014.
  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.
  9. Creasy RK, et al, eds. Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice. 7th ed. Philadelphia, Pa.; Saunders Elsevier: 2014. http://www.clinicalkey.com. Accessed Sept. 30, 2014.
  10. Frequently asked questions. Labor, delivery and postpartum care FAQ004. How to tell when labor begins. American College of Obstetricians and Gynecologists. http://www.acog.org/Patients/FAQs/How-to-Tell-When-Labor-Begins. Accessed Oct. 6, 2014.
  11. Harms RW (expert opinion). Mayo Clinic, Rochester, Minn. Oct. 14, 2014.
  12. 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.