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
What is preterm labor?
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.
What are the risks of preterm labor and preterm birth?
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).
Being pregnant with more
than one baby, such as twins or triplets.
An infection in the
mother's uterus that leads to the start of labor.
the uterus or cervix.
Drug or alcohol use during
The mother's water (amniotic fluid)
breaking before contractions start.
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.
What are the symptoms?
It can be hard to tell when
labor starts, especially when it starts early. So watch for these
Regular contractions for an hour. This means about 4 or more in
20 minutes, or about 8 or more within 1 hour, even after you have had a glass
of water and are resting.
Leaking or gushing of fluid from your
vagina. You may notice that it is pink or reddish. This is called a rupture of membranes, also known as your water breaking. When this happens before contractions start, it's called premature rupture of membranes, or PROM. When it happens before 37 weeks of pregnancy, it is called preterm premature rupture of membranes, or pPROM.
Pain that feels
like menstrual cramps, with or without diarrhea.
A feeling of
pressure in your pelvis or lower belly.
A dull ache in your lower
back, pelvic area, lower belly, or thighs that doesn't go away.
Not feeling well, including having a fever you can't explain and being overly
tired. Your belly may hurt when you press on it.
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
How is preterm labor diagnosed?
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.
How is it treated?
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:
Try to delay the birth with medicine. This may or may not
Use antibiotics to treat or prevent infection. If your
amniotic sac has broken early, you have a high risk of infection and must be
Give you steroid medicine to help prepare your baby's lungs for
Treat any other medical problems causing trouble
Allow the labor to go on because delivery is safer
for the mother and baby than letting the pregnancy go on.
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
What Increases Your Risk
A risk factor is anything that increases your chances of having a problem.
Risk factors related to your pregnancy
Pregnancy with twins, triplets, or more.
Infection in the urinary or reproductive tract,
including the vagina.
Preterm labor isn't always treated. When deciding whether—and how—to treat it, your
doctor or nurse-midwife will think about:
Your baby's weight and age. Ideally, preterm labor is
delayed until a baby is mature enough to avoid problems after birth. When a pregnancy is
nearing term (about 37 or more weeks), preterm labor is usually allowed to continue until
Your health. Very high blood pressure,
HELLP syndrome, chronic disease, infection, or heavy
bleeding can make it necessary to deliver right away.
Your baby's health. Signs of fetal distress or
illness can make it necessary to deliver right away.
The stage of your labor and how fast it's moving along. For example,
when your cervix is well effaced and dilated, medicine to slow labor is less likely to work.
distance to the nearest neonatal intensive care unit (NICU).
If there is a good chance that you could be taken to the NICU, your doctor may try to slow labor.
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:
Slow or stop contractions.
Help the baby's lungs mature.
Help protect your baby's brain. If you're less than 32 weeks pregnant, your doctor or nurse-midwife may give you medicine to help prevent some problems that affect your baby's brain, such as cerebral palsy.4
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:
Drink 2 or 3 glasses of water or juice. Not having enough
liquids can cause contractions.
Stop what you are doing, and empty your bladder. Then lie down on your
left side for at least 1 hour.
If your contractions get worse during the hour, call your doctor
or nurse-midwife, or go to the hospital.
Try to remember what you were doing when the symptoms started so
that you can avoid starting the contractions again later.
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.
Magnesium sulfate. If you're less than 32 weeks pregnant, your doctor or nurse-midwife may give you this medicine to help prevent some problems that affect your baby's brain, such as cerebral palsy.
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
Other Places To Get Help
American Congress of Obstetricians and Gynecologists
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):
ByHealthwise Staff Primary Medical ReviewerSarah Marshall, MD - Family Medicine Specialist Medical ReviewerWilliam Gilbert, MD - Maternal and Fetal Medicine
How this information was developed to help you make better health decisions.