Preterm labor

Date Updated: 02/08/2022

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.

Diagnosis

Your health care provider will review your medical history and risk factors for preterm labor and evaluate your signs and symptoms. If you're experiencing regular uterine contractions and your cervix has begun to soften, thin and open (dilate) before 37 weeks of pregnancy, you'll likely be diagnosed with preterm labor.

Tests and procedures to diagnose preterm labor include:

Pelvic exam. Your health care provider might evaluate the firmness and tenderness of your uterus and the baby's size and position. If your water hasn't broken and there's no concern that the placenta is covering the cervix (placenta previa), he or she might also do a pelvic exam to determine whether your cervix has begun to open. Your health care provider might also check for uterine bleeding.
Ultrasound. A transvaginal ultrasound might be used to measure the length of your cervix. An ultrasound might also be done to check for problems with the baby or placenta, confirm the baby's position, assess the volume of amniotic fluid, and estimate the baby's weight.
Uterine monitoring. Your health care provider might use a uterine monitor to measure the duration and spacing of your contractions.
Lab tests. Your health care provider might take a swab of your vaginal secretions to check for the presence of certain infections and fetal fibronectin — a substance that acts like a glue between the fetal sac and the lining of the uterus and is discharged during labor. These results will be reviewed in combination with other risk factors. You'll also provide a urine sample, which will be tested for the presence of certain bacteria.

Treatment

Medications

Once you're in labor, there are no medications or surgical procedures to stop labor, other than temporarily. However, your doctor might recommend the following medications:

Corticosteroids. Corticosteroids can help promote your baby's lung maturity. If you are between 23 and 34 weeks, your doctor will likely recommend corticosteroids if you are thought to be at increased risk of delivery in the next one to seven days. Your doctor may also recommend steroids if you are at risk of delivery between 34 weeks and 37 weeks.

You might be given a repeat course of corticosteroids if you're less than 34 weeks pregnant, at risk of delivering within seven days, and you had a prior course of corticosteroids more than 14 days previously.
Magnesium sulfate. Your doctor might offer magnesium sulfate if you have a high risk of delivering between weeks 24 and 32 of pregnancy. Some research has shown that it might reduce the risk of a specific type of damage to the brain (cerebral palsy) for babies born before 32 weeks of gestation.
Tocolytics. Your health care provider might give you a medication called a tocolytic to temporarily slow your contractions. Tocolytics may be used for 48 hours to delay preterm labor to allow corticosteroids to provide the maximum benefit or, if necessary, for you to be transported to a hospital that can provide specialized care for your premature baby.

Tocolytics don't address the underlying cause of preterm labor and overall have not been shown to improve babies' outcomes. Your health care provider won't recommend a tocolytic if you have certain conditions, such as pregnancy-induced high blood pressure (preeclampsia).

If you're not hospitalized, you might need to schedule weekly or more-frequent visits with your health care provider so that he or she can monitor signs and symptoms of preterm labor.

Surgical procedures

If you are at risk of preterm labor because of a short cervix, your doctor may suggest a surgical procedure known as cervical cerclage. During this procedure, the cervix is stitched closed with strong sutures. Typically, the sutures are removed after 36 completed weeks of pregnancy. If necessary, the sutures can be removed earlier.

Cervical cerclage might be recommended if you're less than 24 weeks pregnant, you have a history of early premature birth, and an ultrasound shows your cervix is opening or your cervical length is less than 25 millimeters.

Preventive medication

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.

Recent research suggests that vaginal progesterone is as effective as cervical cerclage in preventing preterm birth for some women who are at risk. The medication has the advantage of not requiring surgery or anesthesia. Your doctor may offer you medication as an alternative to cervical cerclage.

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.

Lifestyle and home remedies

Preterm contractions might be Braxton Hicks contractions, which are common and don't necessarily mean that your cervix will begin to open. If you're having contractions that you think might be a symptom of preterm labor, try walking, resting or changing positions. This might stop false labor contractions. If you're in true preterm labor, however, your contractions will continue.

Bed rest to manage preterm labor hasn't been shown to reduce the risk of preterm birth. Bed rest can lead to blood clots, emotional distress and muscle weakness.

Coping and support

If you're at risk of preterm labor or premature birth, you might feel scared or anxious about your pregnancy. This might be especially true if you have a history of preterm labor or premature birth. Consult your health care provider about healthy ways to relax and stay calm.

Preparing for an appointment

If you develop any signs or symptoms of preterm labor, contact your health care provider right away. Depending on the circumstances, you might need immediate medical care.

Here's some information to help you get ready for your appointment, as well as what to expect from your health care provider.

What you can do

Before your appointment, you might want to:

Ask about pre-appointment restrictions. In most cases you'll be seen immediately. If that's not the case, ask whether you should restrict your activity while you wait for your appointment.
Ask a loved one or friend to join you for your appointment. The fear you might be feeling about the possibility of preterm labor can make it difficult to focus on what your health care provider says. Take someone along who can help remember all the information.
Write down questions to ask your health care provider. That way, you won't forget anything important that you want to ask, and you can make the most of your time with your health care provider.

Below are some basic questions to ask your health care provider about preterm labor. If any additional questions occur to you during your visit, don't hesitate to ask.

Am I in labor?
Is there anything I can do to help prolong my pregnancy?
Are there any treatments that could help the baby?
What signs or symptoms should prompt me to call you?
What signs or symptoms should prompt me to go to the hospital?
What are the risks if my baby is born now?

What to expect from your health care provider

Your health care provider is likely to ask you a number of questions, including:

When did you first notice your signs or symptoms?
Are you having contractions? If so, how many an hour?
Have you had any changes in vaginal discharge or bleeding?
Have you been exposed to an infectious disease? Do you have a fever?
Have you had any previous pregnancies, miscarriages, or cervical or uterine surgeries that I'm not aware of?
Do you or did you smoke? How much?
How far do you live from the hospital?
How long would it take you to get to the hospital in an emergency, including time to arrange any necessary child care or transportation?

Preterm labor poses serious risks for your baby. Work with your health care provider to understand your diagnosis and improve your chance of a healthy outcome.