By Mayo Clinic Staff
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.
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
- 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.
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.
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.
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?
- What can I do — if anything — 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?
To help diagnose preterm labor, your health care provider will document your signs and symptoms. If you're experiencing regular, painful contractions and your cervix has begun to soften, thin and open 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. He or she might also do a pelvic exam to determine if your cervix has begun to open — if your water hasn't broken and the placenta isn't covering your cervix (placenta previa).
- Ultrasound. An ultrasound might be used to measure the length of your cervix and determine your baby's size, age, weight and position in your uterus. You might need to be monitored for a period of time and then have another ultrasound to measure any changes in your cervix, including cervical length.
- 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. However, this test isn't reliable enough to be used on its own to assess the risk of preterm labor.
- Maturity amniocentesis. Your health care provider might recommend a procedure in which amniotic fluid is removed from the uterus (amniocentesis) to determine your baby's lung maturity. The technique can also be used to detect an infection in the amniotic fluid.
If you're in preterm labor, your health care provider will explain the risks and benefits of trying to stop your labor. Keep in mind that preterm labor sometimes stops on its own.
For some women, a surgical procedure known as cervical cerclage can help women who develop preterm labor because of a short cervix. During this procedure, the cervix is stitched closed with strong sutures. Typically, the sutures are removed during week 36 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 that your cervix is opening or that your cervical length is less than 25 millimeters.
If you're before week 34 of your pregnancy and in active preterm labor, your health care provider might recommend hospitalization. In addition, your health care provider might give you medications to temporarily halt preterm contractions so that medications can be given to mature your baby’s lungs. Once you’re in labor, there are no medications or surgical procedures available to stop labor. However, your doctor might recommend the following medications:
- Corticosteroids. If you're between weeks 24 and 34, your health care provider might recommend an injection of potent steroids to speed your baby's lung maturity. Corticosteroids also might be recommended starting at week 23 of pregnancy, if you're at risk of delivering within 7 days. In addition, corticosteroids might be recommended if you're between weeks 34 and 36 and 6 days of pregnancy, at risk of delivering within 7 days and you haven't previously received them. You might be given a repeat course of corticosteroids if you're less than 34 weeks pregnant, at risk of delivering within 7 days and a prior course of corticosteroids was given to you 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 may 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 stop your contractions. These medications won’t halt preterm labor for longer than two days because they don't address the underlying cause of preterm labor.
However, they might delay preterm labor long enough for corticosteroids to provide the maximum benefit or, if necessary, for you to be transported to a facility that can provide specialized care for your premature baby.
Your health care provider can help you weigh the risks and benefits of using a tocolytic. In addition, your health care provider won't recommend a tocolytic if you have certain conditions, such as pregnancy-induced high blood pressure.
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.
If you're having contractions that you think might be a symptom of preterm labor, rest, drink fluids and avoid strenuous activity. This might halt false labor contractions. If you're in true preterm labor, however, your contractions will continue. Keep in mind that 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 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. Certain techniques — such as imagining pleasant experiences, doing breathing exercises or listening to music — may help you reduce your anxiety during pregnancy, although these methods have not been well-studied.
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.
Oct. 19, 2016
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