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This topic covers how preterm labor affects the pregnant woman. If you want to know how it affects the baby after he or she is born, see the topic
Preterm labor is labor that comes too early—between 20 and 37 weeks of pregnancy.
In labor, the
uterus contracts to open the
cervix. This is the first stage of childbirth. In a full-term pregnancy, this doesn't happen until at least week 37.
Preterm labor is also called premature labor.
The earlier a baby is delivered, the higher the chances are that he or she will have serious problems. This is because many of the baby's organs—especially the heart and lungs—aren't fully grown yet.
infants born before 24 weeks of pregnancy, the chances of survival are
extremely slim. Many who do survive have long-term health problems. They may
also have trouble with learning and talking and with
moving their body (poor motor skills).
preterm labor include:
Often the cause isn't
doctor uses medicine or other methods to start labor early because of pregnancy
problems that are dangerous to the mother or her baby.
It can be hard to tell when
labor starts, especially when it starts early. So watch for these
If your contractions stop, they may have been
Braxton Hicks contractions. These are a sometimes
uncomfortable—but not painful—tightening of the uterus. They are like
practice contractions. But sometimes it can be hard to tell the
If you think you
have symptoms of preterm labor, call your doctor or certified nurse-midwife. He
or she can check to see if your water has broken, if you have an infection, or
if your cervix is starting to dilate.
You may also have urine and blood tests
to check for problems that can cause preterm labor.
Checking the baby's
heartbeat and doing an
ultrasound can give your doctor or midwife a good
picture of how your baby is doing. Amniotic fluid can be tested for signs that
your baby's lungs have grown enough for delivery.
You may have a
painless swab test for a protein in the vagina called fetal fibronectin. If the
test doesn't find the protein, then you are unlikely to deliver soon. But the
test can't tell for certain if you are about to have a preterm birth.
If you are in preterm labor,
your doctor or certified nurse-midwife must compare the risks of early delivery
with the risks of waiting to deliver. Depending on your situation, your
doctor or midwife may:
Learning about preterm labor:
Preterm labor can be caused by a
problem involving the baby, the mother, or both. Often a combination of
several factors is responsible. But in about 1 out of 3 preterm births, the
cause isn't known.1
Causes of preterm labor include:
often starts without obvious symptoms. But you may notice one or more symptoms,
It is sometimes hard to tell the difference between
Braxton Hicks contractions and preterm labor
You may have one or more of these symptoms and not
be in preterm labor. But if you are concerned, talk to your doctor or
preterm labor occurs close to your due date (in the
35th or 36th week of pregnancy), you may be allowed to deliver without delay.
Preterm birth at this point in a pregnancy doesn't usually cause serious
But preterm labor doesn't always mean
that preterm birth will happen. Your doctor may be able to stop your preterm
When preterm labor can't be stopped, most women can deliver
vaginally. But if your health or your baby's health is at risk, you may need a
A baby born too early may have complications, such as bleeding in the brain or chronic lung disease. The earlier a baby is born, the higher the risk.
Your doctors can prepare you for what may lie ahead. They can base this on your condition and how many weeks pregnant you will be when you give birth.
Thanks to improved medical care, more premature infants are surviving today than in years past. For more information, see the topic
A risk factor is anything that increases your chances of having a problem.
can be hard to recognize. Get the earliest possible medical care by calling your doctor or your nurse-midwife about signs of preterm labor.
Call your doctor or
your nurse-midwife if:
your doctor, your nurse-midwife, or the labor and delivery unit of your local
If you are having painless or mild contractions
that are irregular or more than 15 minutes apart:
If your contractions stop, they were probably
Braxton Hicks contractions. These are harmless and
normal. Braxton Hicks contractions are often irregularly timed and
uncomfortable rather than painful.
Call your doctor or nurse-midwife if you start to have regular contractions.
If you are in preterm labor, you may be seen
continue to see your
certified nurse-midwife or
certified professional midwife, who will consult with
one of the doctors listed above.
To prepare for your appointment, see the topic Making the Most of Your Appointment.
If you have symptoms of
preterm labor, both you and your baby will be
examined and monitored.
Information from these exams and tests can help you and your doctor
or nurse-midwife decide whether to treat early labor and delay the birth or
let it continue.
You will be examined for tenderness
in your uterus. Your temperature, pulse, and rate of breathing will be checked.
Depending on your symptoms, you may have one or more exams or tests, including:
Preterm labor isn't always treated. When deciding whether—and how—to treat it, your
doctor or nurse-midwife will think about:
If your water hasn't broken, you will be observed for at least an hour or two to see if your
contractions continue and your cervix changes (opens and thins). If your cervix doesn't change, or if your contractions stop or
slow down, you may be sent home.
If your cervix changes, you will be admitted to the labor and
In the hospital, your
doctor or nurse-midwife may use medicines to:
For more information, see Medications.
It's hard to prevent preterm
labor, because it usually isn't expected. Also, it's often due to causes
that aren't completely understood.
But building some
healthy pregnancy habits—such as going to all of your doctor appointments and getting enough folic acid— may help
prevent preterm labor and give your baby the best chance to be healthy.
Being pregnant with
twins, triplets, or more increases the chances of preterm labor and problems for the babies.
If you had preterm labor in a previous pregnancy, your risk for having it again is high. Your doctor may consider giving you weekly progesterone shots during your second and third trimesters. Research shows that these shots may help lower your risk of preterm labor.3
But if you're pregnant with twins or more, progesterone treatment is generally not used to prevent preterm labor even if you had a previous preterm birth. Research has not shown that progesterone shots prevent preterm birth in women pregnant with more than one baby.4
preterm labor are warning signs. They don't necessarily mean that you'll have a preterm birth.
If you're less than 37 weeks pregnant and you're having more or stronger contractions than usual, try these things:
Although stress isn't thought to be a direct cause of preterm
labor, do what you can to reduce stress in your life. Try to
do less, ask for help, and eat well.
Strict bed rest is no longer used to prevent preterm labor. But your doctor may recommend expectant management, which may involve some bed rest.
If your contractions are causing changes
in your cervix, or if you have signs of
preterm premature rupture of membranes (pPROM), you may be given medicines to help delay delivery.
Delaying labor even for a short time can allow you to be:
medicines can be dangerous when a fetus is showing signs of distress or for
women with certain health conditions (such as heart problems, severe
preeclampsia, or poorly controlled
high blood pressure).
Cervical cerclage is the placement of stitches in the
cervix to hold it closed during pregnancy. It
is meant to stop the cervix from opening early, which could lead to
miscarriage or preterm birth.
It isn't used to treat preterm labor. But for a woman who has had a preterm birth in the past
because her cervix didn't stay closed, cervical cerclage may prevent another
The American Pregnancy Association is a national health
organization committed to promoting reproductive and pregnancy wellness through
education, research, advocacy, and community awareness. You can call a
toll-free helpline or use the Web site to request patient education materials.
Haas DM (2011). Preterm birth, search date June 2010.
BMJ Clinical Evidence. Available online:
Samson SA, et al. (2005). The effect of loop
electrosurgical excision procedure on future pregnancy outcomes.
Obstetrics and Gynecology, 105(2): 325–332.
American College of Obstetricians and Gynecologists (2012). Prediction and prevention of preterm birth. ACOG Practice Bulletin No. 130. Obstetrics and Gynecology, 120(4): 964–973.
American College of Obstetricians and Gynecologists
(2012). Management of preterm labor. ACOG Practice Bulletin
No. 127. Obstetrics and Gynecology, 119(6):
Other Works Consulted
American College of Obstetricians and Gynecologists
(2007, reaffirmed 2012). Premature rupture of membranes. ACOG Practice Bulletin No. 80.
Obstetrics and Gynecology, 109(4):
Iams JD, et al. (2009). Preterm labor and birth.
In RK Creasy et al., eds., Creasy and Resnik's Maternal Fetal Medicine, 6th ed., pp. 545–582. Philadelphia: Saunders Elsevier.
McDonald S, et al. (2005). Perinatal outcomes of in
vitro fertilization twins: A systematic review and meta-analyses.
American Journal of Obstetrics and Gynecology, 193:
Murphy KE, et al. (2008). Multiple courses of
antenatal corticosteroids for preterm birth (MACS): A randomised controlled
trial. Lancet, 372(9656): 2143–2151.
U.S. Preventive Services Task Force (2008). Screening for Bacterial Vaginosis in Pregnancy to Prevent Preterm Delivery: Recommendation Statement. Available online: http://www.uspreventiveservicestaskforce.org/uspstf08/bv/bvrs.htm.
Yost NP, et al. (2006). Effect of coitus on recurrent
preterm birth. Obstetrics and Gynecology, 107(4):
January 8, 2013
Sarah Marshall, MD - Family Medicine
& William Gilbert, MD - Maternal and Fetal Medicine
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