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 chance of preterm labor, but preterm labor can also occur in pregnant women with no known risk factors.

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
  • 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

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.

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. 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.

By Mayo Clinic Staff